When working my 1958
Caravanner up from "tabula rasa" I used a cylindrical wood/coal "Military Stove" ($60). Following lessons of my state of the art home furnace I moved my tail lights to the bumper and one original 4" tail light opening in the skin is combustion air input and the other is grill exhaust output driven by a 4" turbo fan powered by a rooftop Dutch wind vane w/ wooden gears. Military stove was made air tight and vents into the 4" pipe thru aft roof vent. Stove has 2 stage hydronic coils i.e. first coil is 5/8" schedule K roll soft copper and the second for radiant heat exchangers ( both 1/50 HP pumps powered by the wind vane energy stored in twin 100 pint water storage vessels suspended - as in grandfather clock weights which drop.) As water is consumed it is replaced by wood, or coal or canned goods. 4400 watt dual fuel A frame mounted generator has vertical pipe exhausting above roof. When necessary I can provide 40,000 Btus of interior carbon monoxide free energy. Cost $400. $100,000K+ Airstreams are Model T Fords!!!