You should be OK with what you are doing. I did basically the same thing to our Allegro this year. We have had several nights in the teens here in Northwest Montana with no problems. I have not found it necessary to use the furnace, only an oil filled radiator type space heater. I also keep the water heater on, using electric power. We are leaving this week for a visit with relatives in California, and will will be using the motorhome thru the holidays.