The owner/builder of it built it as a bug out vehicle as well as a cheap DIY stealth camper.
He bought a 2012 12×6 cargo trailer for a little under $3000 and he started to convert it himself.
The under carriage and chassis was coated to prevent rust. He also sealed the roof to prevent leaks.
To insulate it he had to remove the plywood panels, install the insulation, and then put it all back together.” – Alex