Propane tankless hot water heaters IMHO the way to go. We used them all the time for washing the horses at horse shows. And then took it with me when I went full time. Numerous brands to choose from and different sizes of propane tanks needed.
(If you decide to buy one go to the horse websites the same unit sells for WAAY less than if you buy the same thing off an RV site.:W)
Here's just one. Its' the one I used for years.
https://www.ebay.com/itm/ECCOTEMP-5-Liter-Gas-Portable-Camp-Water-Heater-with-Shower-Head-L5-1-5-GPM/382373378473?hash=item59073ab9a9:g:A4wAAOSwg31aeMFS
Girl not included! :B
