Hi Phil and Gary,
Thanks.
Phil, my Ford E-450 won't run the air conditioner in defrost mode. I've toyed with the idea of having a switch added so I could do so. That would bring in outside (hot) air which often might require more "cooling power".
JaxDad, I've tried the rear vent trick, but it seems ineffective in the extreme cold I need to combat.
BoarderCollie, running the generator to produce heat via electrical resistance heating is more expensive than burning propane. It is DEFINITELY more convenient, especially if you are in a self propelled RV where the propane tank is fixed. Most of the small towns I visit can not deal with filling a fixed tank.