Regarding size of shower enclosure:
The 8 sided PVC pipe "hula-hoop" can be as tight a shower curtain rod/space as you chose to make it...
Or as loose/big as you have room for. The important thing to consider, I suppose, is making it work well with whatever you chose to function as your "shower pan". (Mortar tub, anyone?)
I figure I need a couple of shower curtains (overlapping) to make the full octagon circle on mine if I can't find an extra long one (width) to do the job. It will be plastic curtain to make drying it quick for putting it away.
The water source for my shower will be two 5 gal plastic (thick walled variety) water Jerry cans. Both will hold room tempature/cool/cold water and have a hole drilled in the top of each for a tubeless tire valve stem to moderately pressurize the containers, therefore feeding water to the shower water mixer valve. The cool water will go direct to the mixer valve. The hot water feed to the mixer will detour to the gas stove top where a pot of hot water will be heated. The plastic tubing will change to a series of circles of aluminum tubing for its trip though the hot pot of water, and then back to plastic tubing after exiting the pot to continue on to the hot water side of the mixer valve.
The mixer valve will allow a selection of a wide variety of temperature choices, and can be adjusted as needed if the stove top hot water heat exchanger can not quite keep up with delivering piping hot water.
I figure if I am solo, I will fill the 2 jugs about half full of water and the other half of each full of moderately pressurized air.
For my DW I will fill both jugs full of water, and standby to pressurize both jugs equally/simultaneously as the pressure drops using a "T" air pressure hose to both jugs-plus a manual bicycle pump at the T.
Clear as mud?
I have it all designed in my mind, and will finish building it this spring when I return home from snow birding (retired/old guy). I will report back how it works when finished-and after the "shower trials".