I do a ton of reading and research. Based on that, AFAIR, our furnaces are near 50% efficient and are DC hungry. My camping style is off the grid boondocking. I am not tethered to a pedestal.
The buddy heaters are nearly 100% efficient and do not consume any of your precious DC AH. You can tap off of your main tank using a "extend a stay" adapter or via a bulk tap hose. Be sure to keep all tanks outdoors. I use mine to take off the morning chill and to do an evening warm up. It is quite effective.
Venting is needed to remove moisture which is the natural byproduct of combustion and to let in some O2.
I would never chance running it overnight though.
