Im geared to 0 degrees. I brought up that that i took a tent on a backpacking trip last week instead of my tarp on a fb ul page. Its doubled walled. I had condensation on my quilt in the mornings. A few toldme they used these candles to stop the condensation and that it also added warmth
If you didn't have condensation dripping from the walls of the tent, then the condensation was coming from you, in a manner of speaking. If you bring a light covering for your sleeping bag in such a situation, the condensation should travel to that and stay off of your bag, FWIW. And, anyway, many quilts/bags have a DWR outer, so a bit of condensation on the top isn't too much to worry about, just wipe/brush it off with a rag/bandana/etc.
Also, any such combustion produces carbon monoxide. Not good, and the more your tent is 'buttoned up' the worse that is.