I too used a heater/cooker for years. This year I bought a Mr Heater Buddy Portable. I was pretty disappointed. Heat output was dismal for a 2man flip shanty on a cold day. It also is VERY sensitive to being moved. Mine shut off a few times just from being jostled. It also kept shutting off randomly, maybe the CO sensor. IDK because I had the shack ventilated pretty well. Any more ventilation and it would have been pointless to run Buddy heater at all because it can't put out enough heat to compensate.
I'm back to using the heater/cooker now. More heat output, lighter, less finicky.