I use a Mr Buddy in my Tepui Autana. With the annex down below I just leave the heater down there on high and it heats the entire set up. I'm a little weird about sleeping with it on as well, but I've done it in my normal ground tent a few times. At 32 degrees its gotten the Tepui to a comfy 67 inside. Usually I leave it on for 45 minutes or so before bed and it takes the edge off everything. Its got a knock over shut off and low oxygen shut off, its also approved for indoor use and will heat up to 200 sq ft. Still can't sleep well with it on and to be honest I never trust it in the off position so when I'm done using it I just leave it outside the tent. Also, for anyone that uses one, try lighting it outside the tent and wait for the white catalyst thing to get hot. Then put it in the tent and it doesn't stink one bit after its lit.