Basically just using the bottle as the body of the stove, think 20lb propane cylinder. Cut a hole in the top add air intake and door and off you go. Not a bad idea so long as the cylinder is well vented first. A precaution friends used to take was to remove the valve assembly, after letting it sit for a week or two put it on a fire for a while to burn off paint and any propane.
check out the Kandle Heeter. Eccentric guy, but the multiple pots over a candle or two makes a lot of sense, will trap and release heat very efficiently.
The link there shows how to make it pretty easily I think.
I'll be making a ducted version of the heat stick, drawing hot air from the cabin top and circulating it at foot level, but that only works when you've already got heat in the cabin.