My camper has a built-in LP gen too, but like you I don't even want to consider running it 24x7 to keep the camper warm. The LP wouldn't last very long and the noise would be intolerable. Winter camping is one of the reasons I have a Yamaha 1K generator. I COULD carry enough fuel to keep it running 24x7 for several days, and 99% of the time it would be all the power needed. It's noise level is also very tolerable. The LP furnace is used sparingly, and a ceramic heater is run on its 750 watt setting most of the time. Fridge is on LP all the time, WH is run only when needed. When the microwave is needed, I run the built-in genny.
:):)
