My suggestions would be to have a place for a porta potti for traveling but move the porta potti outside into a cabana type tent if you are staying long enough to make it worth the move.
If the mechanics can be designed, make a drop floor that is able to be lowered when camping, maybe lowered to the ground, or within a couple of inches of the ground, then be able to raise it to give 7-9 inches of ground clearance when hauling.
An outside galley would be nice but not required. Set up cooking on a picnic table or portable table. I would prefer cooking outside but maybe a place for a coffee pot inside.
The Squidget is close to a standie. It has a goucho bed.