I've been thinking about this lately too, as I plan to spend a month in the
NW US snowboarding this winter. (yes, living in the van!) My thoughts thus
far are to add a small extra hose from my Propex funace through to the water
tank compartment, basically to keep the water from freezing, since in those
cold temps the furnace will be working a lot anyway. If I need hot, it's
only a few minutes on the stove. Maybe also have a shutoff valve on this
extra hose for when the temps aren't really that cold (yeah, right) It would
be cool if some company made a little propane-fired water heater we could
install-is there such a thing? That's all my thoughts for now.

Karl