I too grew up with the Coleman catalytic heaters in a tent. Back in the 50s-60s they were boss to have...
Knowing what I know now as well as knowing a couple of camper friends that have had serious effects with Co poisoning I don't think I would do it again...
The only one I would even consider now is the vented WAVE 6 propane heater.
Hopefully you can find cabinet space in the POPUP to accommodate something like this...
We do alot of camping off the power grid in our OFF-ROAD POPUP camper and the built-in propane furnace is just way too hot for us to use. The furnace drives us out of the trailer being so hot. It also uses the VERY LOUD DC fan which is also very power hungry. Ours draw 6-8 AMPS from the battery system.
We are considering changing to a HYDRONIC 6-gallon Hot Water Heater mod which a few others have done and worked out great for them... This mod to our hot water system would replace the propane fired furnace and the AQUA HOT 100/200 unit would be installed in the location of the removed furnace. The hot water doesn't take much propane to keep the water temp up and the 12VDC axial fans also operate with a big reduction in current drain as compared to the propane furnace fan. I'm looking at a 50% reduction in battery usage as far as making heat is concerned. The cost of this mod is probably going to be around $350... The AQUA HOT 100/200 heater and the hot water water pump being the high cost items. the Aqua Hot 100 is rated at 4000BTU and the 200 model using two AXIAL FANS is 6000BTU...
Roy Ken