I did make a outside shower stall for 2 out the back of my van, 3/8 electrical conduit, 3/4 pvc pipe, 3 black shower curtains, 1 shower curtain with pockets, 2 2 gallon chemical lawn spray bottles painted black, 4 foam interlocking floor pads, less than 40 bucks to do this
painted the spray bottles black to absorb heat from the sun or in the case a few weeks ago we used the bonfire to help with the heating, had to shake it up a little to get the cooler water from the bottom to mix up and it was like bath water all weekend when I needed a shower
after the first night between me and the wife we only used half of one spray bottle between the two of us, and she has long hair which made for rinseing conditioner out a pain in the butt