Mr buddy propane heaters work pretty well, have never killed me. They do produce water, so you'll need to deal with that.
I prefer a wood stove, but then my buddy is convenient.
The buddy heater works for me also. I have a Cabelas Instinct-6 Guide tent that's about 9' diameter. I run the Buddy Heater with just the pilot light during the night and then turn it up just before we get up in the morning. Can't run the Buddy Heater on high for very long because it gets too hot inside the tent.
People are right who say that a Coleman 2-burner lantern puts out lots of heat. That works also but you want to be able to turn out the lights at night. Then you shut off your heat source.
For my wall tent, I use a wood burning stove.
