I used Mr Buddy heaters all the time (and still do) when tent camping. My back-up heat source for my POPUP trailer is the same Mr Buddy heater.
I follow open windows and vents when using the Mr Buddy heater which almost defeats the reson to have a hearter going if you have an open window... Being TENT FABRIC in the tents and popups sort of make it ok in your mind all is ok to use these type of heaters. It probably is a dumb idea for tents as well. My MR BUDDY heater also puts off a large amount of water during the night. I have it sitting in a cooking tray an it is entirely filled up by morning.
Being in a closed area I don't think I would trust the MR BUDDY heater concept as these heaters remove all of the oxygen inside the trailer and replaces it with Carbon monoxide poison fumes...
This install on google shows what one guy did with his WAVE type propane heater venting it to the outside. This is probably the only way I would ever use an external propane heater in a closed up trailer.


just my thoughts here...
Roy Ken