mm, great concept. A diesel stove or furnace. Being from one of the coasts and seeing them in lots of boats; I am not sure about cheap and dangerous. They are used worldwide in all kinds of marine applications. If installed properly, they are no different than wood stoves; and I have seen a few of those installed in campers!
Just Googled and found a Newport. Heat Output: Low: 6500 BTU High: 16250 BTU
here's the kicker. Consumption. If I have done the math right. Don't shoot me if I am wrong, it's Friday.
Fuel Consumption / 24hr: 1.29 gal LOW 3.20 gal HIGH 3.20 gals and up here on Vancouver island diesel is going for 1.40 per liter, which X 4 of convert nicely to 1 American gallon.so, 5.20 per gallon x3.2 gals on high. That sucker will cost around $17.00 to run full out.
Propane consumption, rule of thumb: A gas guy told me that one could count on 1 lb per hour per 20,000 btu's. I can get 20lbs of propane at Costco for about $8 last time I filled my tanks. $.40/lb, say 40,000 btu heater, $.80/hr on high.