Being a two-door Jeep guy, I'm always looking for saving space. I think I've mentioned this before, but about three-four years ago I bought a pop-up toilet for my privacy tent. It's in a nice round case that unzips. It then pulls out of the case and poops... oops... I mean "pops-up," and easily folds back down. Instructions say that it supports 330 lbs. (which is more then my wife and I weigh combined!). It also comes with 12 individual bags (yes bags!) with absorbent powder that works. I still do double bag.
Honestly, my wife's number one obversion to camping is the lack of facilities, but she'll use this at night when no other facilities are available. I think it's great! It could sit up higher, but that can be fixed with some blocks of wood. It's made by Black Pine, if it's still available?