Instantaneous Hot Water While Boon-Docking

We're RV wannabes and still learning so please pardon the ignorance of my question. I'm very interested in the tankless water heaters. Just makes more sense; less weight, greater fuel economy, etc. My question is, can you still boondock with a tankless water heater? Or are you limited to a direct water hookup? Virginia S., (Dix, IL) 

Indeed you can still boondock with either of the two available brands of tankless water heaters, Virginia. They are both powered by 12-volt DC battery voltage and burn propane, so as long as the battery bank is healthy and you have propane aboard, you can still have hot water flowing from the fresh water container via the on-board water pump. No need for cold showers. Ever!