Depending on your budget, you could always build one or have one built/modified to your specs.
This is my mates van. He built it himself, based on the chassis of a duel axle car trailer. It is ideal for his family and kids. On the inside there is queen bed and 2 sets of bunks (top bunks fold against the walls so the bottom beds can be used as seating also. Small sink and heaps of storage, a microwave (they have a bub), gas hot water system and a spot for the porta pottie.
All cooking and refrigeration is on the outside, sink, gas burner for a camp oven, proper 2 burner BBQ, hot and cold water, slide out fridge and esky, pantry and heaps more storage on the other side.
It is awesome. He was originally building 2 one for me also, however I went in a different direction because of some of the places I wanted to go, I look at his with envy when we are set in a Caravan Park though.
He built this for about 30 - 35k all up out of caravan materials, the frame is also 50 x 50mm fully welded alloy, no timber in the structure.
Regards
Jas