i rigged up a nice solution for our van. One hula hoop cut down to size of a ~3ft diam kiddie blow up pool (~6" deep). Standard shower curtain hooked on hula hoop and base of curtain falls inside of pool. Takes ~10 breaths of air to fill pool, hook hoop on interior roof of van, pump up insulated 1 gallon garden sprayer filled with 50/50 mix of boiling/cold water and we get 2 five minute showers back to back. Hole thing folds down to ~2" by ~38" in a bag.
sounds like a nice solution, any picture ? having a hard time imagining what it would be like