I'm working on a design for a camper built around a Promaster 136. I'll share design details as the drawings get to be a bit more consumable. With a degree in engineering, I'm naturally interested in the physics of the van design as well, especially the use of air conditioning, which seems very problematic when not on shore power. I have a blog www.mindfultrek.com where I'll also be posting some things. I have the design programming posted there already in case you are interested.