I have a propane heater - it's a ceramic plate deal that can hook up to small bottles or large bottles. I do worry about the CO2 output so I make sure I have decent air flow.
Really all I do is turn it on before I go in, heat the space up, which is insulated mind you and turn it off before I fall asleep. I crack the window a hair, also crack to top vent, and leave them open all night.
Its a little colder on the floor for the dog, so Im thinking about a insulated foam mat and then a bed to put on it for her.
One sleeping bag and I'm laughing man, sleep is nice and toasty, but not too hot! Im going to be heading out pretty quick here, Im due for a good trip.
the make of my heater: