So I think I've got the water situation figured out. Almost. From what I read, the best water tank will be situated under the trailer above the axle. I'll have to get the dimensions to find the right tank - but I don't think it'll be something I find on Craigslist or on the inexpensive side. I'm not sure where I'd place the fill hole (with vent cap). From there, it looks like the Flojet auto pump is pretty inexpensive ($50 on Amazon). I had thought about skipping the tank and getting a simple submersible pump, but I can't find any that will work my hot water heater. Any suggestions so I could drop a pump in my water can? From the pump, I'd run a T - one to the water heater and one to a faucet somewhere on the back of the trailer.
The other option is a-la Adventure Trailers and mount a water tank on the tongue and plumb it under the trailer. I know my plan is to eventually haul the moto on the tongue though, so I'm leery of over 500lbs of tongue weight (against the rules). But maybe I sacrifice the moto carrying for simple backcountry? It would be nice to have the hot water heater for a shower and 6'' bed pad after a day of desert riding!