Does anyone use Marine Heaters in their campers? I would think the Dickinson Propane
Heater with a shield would make a great heater and not require and electricity to operate it.
Also, I like the diesel stoves and heaters Dickinson makes. You could go a long time on a 55 gal drum of diesel.
The Newport model is bulkhead mounted--would require a heat shield, and burns 1.29 to 3.2 gal per 24 hours at 6500-16,250 btus.
A 6 gal jerry can would last 2-5 days. A 55 gal drum would last 17 days on high and 43 days on low in continuous use!
I would seriously think about a diesel heater or a diesel stove.
If you don't like the smell of diesel, a Dickinson propane
heater. They have two models:
A 5000 to 7000 btu heater that last 140 on low and 100 hours on high, or,
A 6000 to 9700 btu heater that lasts 110 on low and 78 hours ob high.
These are safe vented heaters. They are not cheap, but if you camp frequently, or long term like a full timer. I think they make sense.