I'm currently trying the WaterPort having tried to ho-make one out of ABS black plastic and coming to the conclusion that it was just too much work for what I would get out of it.
It's kind of funny, on the WaterPort website, they don't really emphasize using it as a human shower, more like washing the dog or squirting of a dirty bike or surfboard.
Well, for good reason, it's grey plastic and in my (short) experience with it so far, it does a very poor job of heating up using heat from the sun, so I don't really think it's sold under that premise.
My intention for future use is to be able to:
1. be able to heat up the water in the W/P by recycling through my small water heater from
ZODI
2. pressurize the tank again with my on-board air or even a CO2 pellet or something. (max pressure should be below 45-50 psi in the tank)
It only holds 3.3 gallons, maybe enough for a decent shower if you're economical (i.e. not a teenage girl).
And the weather is warm enough to shower outside!
My next move might be to get one of those RV instant / tankless hot water heaters.
FWIW, YMMV.
Dan.