Thank you about all your advices! It’s very rewarding. After few research, I will change a bit my plan and buy a roof tent instead of sleeping inside the car. This solution will give me more space to make a better inside organization.
The reason to thinks about realize my own “4wd motorhome” is because until now I had not seen any good inside organization. And if I will live during one year with my car, I want to be sure that my solution is the best for my daily use. I’m conscious it could be difficult sometimes, but I’m really manual, and good with 3d and 2d plans, I will prepare all the layout.
Moreover, the idea is to work for free in a farm for 2 or 3 months (I ever had an experience in a farm 1 year ago during 3 months in England) and working during the half of the day for the farm and the rest of the day with my 4wd. The Idea is to use all the tools they have to help me in my project. I will help them and they will help me, I think it could be a great deal for them and me too (if you know good address near Melbourne or near a big city, please let me know)
I don’t want to buy a motorhome or a caravan package because I want to be 100% freedom, go and sleep everywhere I want on the west coast and around the country (with the respect of the local rules and throw the garbage in a good place of course)
The Idea to bought a 4wd beforehand could be good, but I will prefer to see the quality of the care before to buy something and I know no one in Australia. how can I trust someone I don't know?
And yes, buying used vehicles could be dangerous, I will obtain lot of information about parts I need to check before to buy it. I have a little experience in mechanical, but not at all in 4wd. If you have good advices about verifications, please let me know
And yes, I still have the idea to get the dimensions of the GQ!