On most days here my 15,000btu sunflower heater on full isn't enough to melt the ice that forms on the inside of the hut.
This was a balmy December day.
I have used a friends buddy heater in my camper in Alaska and it works well.
I have heard of the wind issues with the pilot lights as well and have read about the fix for that issue on IS.
I do find they go through propane quickly and an external tank would be well worth the $$$$.
I use a 5# tank on my sunflower heater and get 2 days worth of heat out of it.