New Full Time Camper in need of insulation advise.

Your pretty much out of luck there. Even my well Insulated trailer propane has cost me up to 80 dollars a week. On top of a 150 dollar electric bill. RV's are just not well Insulated and nothing outside of a complete wrap in huge sheets of foam board are going to help much. Covering Windows with shrink wrap from a home improvement store might help some, and is cheap. Insulating over all openings might help a little. But bottom line lots of blankets until it warms up is about all you can do.