I bought a portable unit for emergencies, it is a "Sun Rite Tag-Along," sort of like the Mr. Buddy portables. It fits one small Coleman-sized bottle inside, but I bought an adapter, hose, and in-line filters (important) to use 20 lb BBQ tanks.
I used it once. The automatic "keep full" policy of the furnace fuel supplier did not adjust for the colder weather last winter, and we ran out one day for at least 12 hours. I set up the portable in the kitchen, and the air around it did seem warm, though understandably it did not heat the entire house.
We have the standard RV furnace in our camper, which alternates between freezing and roasting when used on a cold Columbus Day night. Between the noise and the battery drain, I am inclined to use the portable catalytic on the next cold-weather trip.
If I do continue to use the RV furnace, one project might be to move the thermostat next to my bunk, both for ease of adjustment and also sensing the temperature near where we actually are at night.
I have read the reports of a lot of full-timers who spend some time boondocking installing the built-in catalytic "Wave" heaters instead of using an RV furnace. I have not heard anyone complain about them.
Someone said "Making good decisions comes from experience, experience comes from bad decisions." I say there are three kinds of people: those who learn from their mistakes, those who learn from the mistakes of others, and those who never learn.