A wood, charcoal, or coal fired heater is a total pain.? I've been in a cabin heated by a wood stove.? It gets way too hot at first but doesn't last more than a few hours, and then it gets way too cold.? We actually found that coal burned the longest, but coal is nasty.? And its inevitable that they'll have a backdraft down the chimney at some point due to wind and/or the fire getting cold, and that puts a bunch of smoke and ash inside.
They make gravity feed vented propane heaters that use no electricity, and don't exhaust gases indoors.? A friend of mine has one in his trailer.? The problem though is they mount on a wall and need a chimney.? Not too practical for an aframe. Here's an example:
