Just saw an article on this in Gizmag. I have no vested interest or knowledge beyond the links below. Just thought someone might be interested as we're often discussing shower options and such.
With the Road Shower you can have pressurized water wherever you go. It will heat the water while you drive and will be ready to give you a high pressure hot shower at the end of the day. Hot or cold, the Road Shower has many uses from the camp hose for dishes, gear, pets, or for extra drinking water.
Road Shower website: http://www.roadshower.com/index.shtml