jlester,
You can use the advanced search tool at the top of the page to assist in finding previous threads on this subject.
To get you started try:
http://www.airforums.com/forum...ghlight=shower
I'm sure you could easily fabricate an aluminum door to adapt to the housing. Furthermore, you could have all the portable fittings stored and/or affixed within one of your storage compartments with the valving there. Just take out the hose & shower head and connect it to a small holder attached to the outside skin when in use. Stow it away when traveling. (hot & cold too, if you install it close to the water heater)