For a temp shower look at camp showers, or you can convert something into a shower like I did over 40 years back:
With an extension, its works as a shower this is in "wash station" mode:
I either forgot or could not find the extension but the privy enclosure doing double duty, setup right outside my tarp canopy as it was about 40 degrees out...:
The above is my big 5 gallon main setup - below is a one gallon version converted from a fire extinguisher - handy as its small enough to heat directly on my stove if the sun does not warm it enough. I have showered fully, hair wash and all, with one gallon -its a get wet, scrub, and rinse deal, but works.
And the one that started it all -from a soda-acid extinguisher:
You can also make these from a Hudson sprayer BUT use a new one, not one that has had god-knows-what in it. You can't heat it on a stove (plastic) but you can boil about half the water and get a good warm temp once mixed.