Hi,
if I was building a camper to be permanently mounted on the back of a truck, I would use a glind heat exchanger to heat water cycled from a 15L insulated cylinder.
Free heat from the engine cooling system, and no need to run the motor just for hot water like the recommended usage.
15L would suit us for end of the day showers and maybe some left over for wash up etc.
Haven't figured out how to adapt the idea to a camper trailer or slide on yet, but may give it more thought.
cheers

