Car camper conversion

@SR @DC 

Hi Sébastien, Hi David,

I am currently working on a project to convert my car (camper) so that I can go on a road trip. As I am new to woodworking and don't have enough equipment, I am asking for your help today if possible :)
Whether it's about the design or layout, or even the construction, I'm sure your advice will be invaluable.
NB: I've made a 3D model to start with, which illustrates my idea.