We built our own Mercedes-Benz campervan from a 1998 412D Sprinter back in 2001. Here are some pictures of it's construction along with some of it touring around Australia.
When we decided to build a Campervan we realised we had some special requirements. Firstly we wanted our children secured with proper retractable seatbelts (unlike most campers), we also wanted to have seating for as many as possible so our kids could invite there friends along. The design we settled on is legally registered as a 8 seater with 5 occupants secured with retractable belts and the others on the rear bench seat with lap belts.