More batteries would be one possibility, I guess -- I already carry two group 31s, and the trailer is so small that there is just no room for more of them on the tongue.
And Steve, I already have a hot water recycling system that I cobbled together -- it is pretty crude, but it gets the job done. But I would rather have a "set it and forget it" infrared heater underneath the tank.
The fact that none of the experts have said "sure, go ahead, put a radiant heater underneath," tells me that this is probably not a winner.
