Clearly camping with a truck offers so many more options for "stuff" than backpacking. When backpacking I used a "big" 3-person tent that could be heated with a candle inside a candle lantern. Small backpacking tents seem to heat up some with just heat from people.
From what I've read the Mr. Buddy heaters are engineered with a lot more safety features than basic propane heaters used to have. Like anything else in safety, with the right skills one person can be safe while an unskilled person is not. A canvas tent is far more flame resistant than nylon, and it was generally large canvas tents that had coal stoves and such.
REI has a bunch of videos that may help. They are my preferred supplier for all things camping and cycling. I have been looking for my backpacking Therm-a-rest but can't find it. A buddy of mine is an engineer for them. Good stuff.
I don't think that anyone mentioned that you are looking for a mummy bag. They are toasty warm for winter camping. Not much room. Pack small.
Another consideration is that the bigger safety issue is sleeping in the presence of combustion. You may not need the heater while in the sleeping bag. But perhaps it can make getting up in the morning nicer.
That said, in man my winter camping, I've never brought a heater.
I am reminded of when Kate plus 8 visited Sarah Palin in Alaska. The kids loved being there in the rain. But Kate had a meltdown. YMMV.