I mounted a small composting type container on the inside of the right hand door in front of the sink. It has a lid, a handle and a braket for easy removal. It came with the composting green rolling bin that the City provided for recycle.
We compost in our own stalls. When I mounted it I made sure it was in the right position so as not to interfere with the door and could still be removed easily. It isn't large capacity so it may mean an extra trip to the dumpster if required but it frees up the floor space and isn't an issue on the road.
Married To The Navigator
2005 Red GMC Duramax 4X4 HD Crew Cab
4" Magnaflow, Banks Air Intake
Firestone Ride Rite Air Springs