Our camper trailer, a hardside A-frame pop-up, has a 6-gallon water heater and an outdoor shower hookup (and no indoor toilet or shower--only a single small hot and cold water sink).
We purchased a pop-up shower enclosure and a 4' x 4' x 3" high foldable "pan" inside of which the enclosure sits. We set it up next to the driver's side of the camper adjacent to the shower fixture door. The pan has a standard hose outlet in one corner. By placing the outlet at the downhill corner, we can drain the gray water into a bladder or portable gray water tank, thus keeping in good stead with the NF, NP, BLM, and State Park CG prohibitions against dumping gray water on the ground. The shower enclosure is our privacy screen for the porta-potti, too. It looks a lot like Rotti's and may be exactly the same unit.
While it's great to have abundant hot water for showers (and dish-washing, etc), the enclosure, pan, hose, and gray water catchbasin are a bit much to deploy when on the road reaching one's destination. We thus used ours sparingly, only while at Twin Lakes, MT and on Rock Creek, MT, as while at other sites for > 1 night, there were either showers available or we just did without.
Foy