This would allow me to sandwich rigid foam between the metal uprights, and skin the exterior and interior with 1/4 and 1/8 plywood. I would like a child bed on the extension over the cab, and I could either build a platform that rests on the wheel wells to allow for some shallow bottom storage, or build upright cabinets in front and behind the wells. I don't think I can incorporate a kitchen with this design, but might be able to create some sort of chuckwagon box.
This would allow me and my son to go camping with relative ease and at a moments notice. My wife has started a new job, and while she now only works 3 days a week, it is Friday-Sunday. Ugh.

Do you think this would be a good starting point?