A friend of mine had an old escort van that he slept in. One side was a cooker, cool box, storage and the floor was foam and the walls were insulated and covered in plywood and carpeted. From the ceiling he had various holders for various things. When he went travelling he add a roof top box. There was also an awning across the rear doors. Very basic but functional for two people. You would be able to do the same with a van of the same size.