I hate to rain on the parade, but the combination of monoxide poisoning and fire trap this contraption presents is a stunningly bad idea, in my opinion. Cracking the window a bit wouldn't do it. If you were lucky, you'd be unconscious or dead before the flames consumed you.

In my foolish younger years I once slept in a van that had a propane lantern going for a little heat. I'm figuring it burns a lot cleaner and puts of less volume of exhaust than that burner. I cracked the window an inch or two for safety. In the morning I was downright woozy and ill, and it took me a few days before I started feeling somewhat normal again, or perhaps just got used to living with a good percentage of my brain cells missing.

I have a camper with a legitimate propane furnace, with its combustion vented outside the camper. There is still a CO detector, and I'm still slightly nervous with the thing running while I sleep.

Carbon monoxide is scary, dangerous, sneaky stuff. Even if it doesn't kill you, it can permanently disable you. It can sneak up on you, gradually putting you to sleep without you knowing it.

I appreciate your interest in finding a working solution, and am not trying to give you a hard time about it. I would just hate to read about you having a tragic accident.

David