How to build the Ultimate Overland Rig
First of all, let me clarify this: There is no golden rule to follow and there is no such thing as an "ultimate overland build"; the effectiveness and efficiency of each Rig depends on a few specific factors, that mainly have to do with the people driving it.
People are different, have different needs and travel in completely different ways. This means that there isn't a vehicle that fits all needs. So the main 3 factors that actually play a crucial role into building your dream overlander are:
1) For how long are you gonna be travelling?
2) How many people are going to be travelling with you?
3) Where are you going to be travelling to? What type of climates, terrain & countries?
Addressing these will definitely differ drastically from person to person, a vehicle built for the needs of one person, most probably won't suit the needs of another. So, lets go and try to address these 3 different questions.

For how long are you going to be travelling?
One of the first question to ask yourself should be the timeframe of your trip. A lot of people build really cool rigs for their weekend escape, trying to get away from the cities, reconnect with nature and get their monthly dose of adventure. This vehicles can be anything from pickup trucks to 4x4 wagons and SUVs equipped with roof top tents, water tanks and power supply to usually last from 2 to 5 days of off-grid travel. These needs are going to be completely different from someone who will be travelling for 6 months or even a year or two in a row.
For a long-weekend adventurer, in most cases having approx. 4L of water per person per day, a place to charge your phones and cameras, some recovery gear and a way to have a nice relaxing sleep, sheltered from the elements, you should be more than good to go. There isn't even a real need for a 12 fridge/freezer, if you mostly travel during cold months.
So, set your goals, if you are not going to be a full time overlander, then you probably need a lot less than you think you do, in order to explore safely and have fun. The "a-lot-less-than-you-think" part is something really important, as overpacking and adding unnecessary weight on your rig is literally your enemy - and this is a skill that you'll build as time goes by and as you go on to more and more trips.
During our first 3-day trip, 4 hours away from home, we literally packed like we were heading off to an expedition on a new planet; while during our latest trip across southern Europe, lasting a month, the rear sits of our Land Rover where almost empty, carrying far less stuff. Pro tip here: its a really good idea to pack you clothes into hard boxes, makes it way easier to find what you are looking for, you can have a flat space to work on and you can keep everything way more organised and tidy.
So, Don't overpack, know how many days you need your rig to be self sufficient and preferably go off to smaller shake down trip(s) before you embark for your big adventure.
Another point to discuss here is the sleeping arrangement. First of all, a roof top tent is something that can work with both a short and a long term overlander. There are countless of people who have travelled even with a soft-shell tent, thousands of kilometres, over many countries, for lots of months. On the other hand, for full time explorers and travellers, something like a canopy camper might be a bit more sensible since its easier to have a place to relax inside the car, if the weather gets, unexpectedly, really bad, or you just need 4 walls around you to do some "office work".

How many people are going to be travelling with you?
Another equally important question is the type of vehicle you actually need for your trip.
If just like us, there's only two of you travelling, then you can literally make it work with an SUV and a roof top tent, to a pickup truck with a canopy camper. Whatever makes you feel more comfortable and safe. Again remember the time frame discussed above when choosing your set-up.
If you travel as a family, especially long term, it's better to either consider two roof top tents on a pickup truck or going for a canopy camper, as you'll feel more comfortable with not having to share a 4-people tent and have two actual seperate living spaces. If again this is your weekend gateway, with occasional larger trips, then a larger, 4-people tent can work great there as well.
People are also carrying their own individual stuff, so all these should be taken into consideration, meaning higher vehicle payload, larger fridge, more space etc.
Where are you going to be travelling to? What type of climates, terrain & countries?
Now, this gets really interesting! Where are you heading off to?
Combining the two points discussed above, the final point, which has to do with the actual destination, should not be overlooked. A vehicle setup, build to tour the Mediterranean coast can be very different from a vehicle built to travel across Norway or even Iceland. Again this doesn't mean that this can't happen, we are just discussing ways that will make the trip more comfortable and overall, more efficient.
Some subquestions you should ask here are: how much off-roading (if any) are you going to be doing? Do you really need Mud Terrain tires? Are you gonna go over deep mud, sharp rocky areas or beaches that have lots of pointy sticks that can easily go through a more road-focused AT tire? Because if you don't, then it might not worth the extra fuel consumption, noise, premature ware and the extra investment you need to get a set of 5 Muddies. Although yes, we know, they look way cooler. Tires are probably one of the most important aspects to pay to and its true, size does matter when off roading, but are you really gonna be off roading?
Suspension consideration is also really important. Apart from the added clearance, suspension is going to be responsible for carrying all the added extra weight added to the vehicle; so it's wise to choose something that is reliable, tested and proven.
Going back to the sleeping arrangements, a canopy camper is generally better suited for lower temperatures, as combined with a heater, you can have 4 walls and a warm place to sit down and relax, as a blizzard is changing the landscape outside. On the other hand, a quality hardshell roof top tent can also stand against harsh weather conditions and can even serve as, a smaller, living area when the weather gets bad outside.
We've used our Feldon Shelter Hawks Nest in almost all conditions possible, high humidity, strong winds (really strong winds), rain downpours, snow and temperatures way below -10C. For people who want real adventures and really want to go out there and explore, the choice of quality, tested and proven gear is probably on the most important factors to consider, as the last thing you need is a leaking roof while being in the middle of nowhere.

Now, the actual vehicle itself also matters here. For example, a huge expedition truck can only get you up to some points (despite offering home-like ammenities for long term overlanders). Places in Europe can be tight, even for a Toyota Tundra or an F250 to navigate through. So again, make a plan of the routes you want to follow and make sure your vehicle can actually drive through these routes.
Talking about routes, it's really important to point something out. Do a research of the place you want to visit, avoid protected areas and don't try to test the off-roading limits of your vehicle and yourself. Respecting and preserving the natural habitats is THE most important thing we can all do during our travels. Do your part and leave them better than you found them.
Choice of Gear
So despite not being part of the 3 main question to ask yourself, choosing the right gear is equally important, as it is a safety concern and something that can even ruin your entire trip. Some things that really need serious research (and probably are the bigger financial investments) are Tires, vehicle parts, suspension and your living area - sleeping arrangement. For us the reason why we went for Feldon Shelter as our roof top tent choice was simple (and to finally end up being the importers of the brand in Europe) was that their RTTs are made to last in New Zealand, a place where the Sun is burning during Summer, strong winds are blowing almost all year long, snow and rain are somethings you'll definitely face quite frequently and above all, something really really important, high levels of moisture. Thus a roof top tent designed for all these is the thing we needed to boost the reliability of our build against changing weather conditions.
RELIABILITY AGAINST THE ELEMENTS - is something you should keep in mind while building your rig - a high quality tent to protect your sleeping area and your resting time - a reliable tested and proven suspension system and tires that will last of many kms in rough, changing terrain are the things we'd seriously look into, when building our vehicle.
So, as you can see there couldn't possibly be something like the Ultimate Overland Build, simply because people are different. Plan ahead, identify your needs and do test runs before your big trip are the 3 things to keep in mind!
PS adding a fourth one, make sure your vehicle looks nice as well, by parking it and pay attention whether you look back to admire it. Then you probably got it right.
