For short distances from a water source to a camp, I carry four 7 gal Reliance jugs on the rv floor.
To eliminate the lifting, I have a specific clean tub that I pour it into and a specific marine bilge pump that pumps it into the holding tank when needed. I just plug the bilge into my outside solar hookup. That's actually a 2 way 12v power source.
Re the roof: I would rather see that much weight on a front receiver rated at 500# or more if possible. Some of the TC guys carry it that way.
The other option would be an outside portable shower and use a stream as your water for washing .
I also bought from Amazon a portable rechargeable shower head and pump that is submersible in a 5 gal bucket. I have used that inside my shower using stream water. It actually works in the winter when I have winterized my lines. I just drain the gray tank right away.
