You could get a Mr. Heater portable propane heater. We have the Big Buddy model ourselves (http://www.mrheater.com/productdetails_extended.asp?catid=41&id=116). We use it a lot while boondocking in our motorhome when we don't want to use the generator or drain our battteries. They run about $120 or so. Get a bunch of the disposable one pound propane cylinders at Costco or Wallyworld, and some D batteries to power the fan. As long as you don't put it on HIGH it will run a long time on two cylinders, and will keep at least one normal sized room pretty warm...