"mid price" monaco in the winter?

In your place I would certainly not try what you are proposing. Even if you could heat it all winter, I think it would be very risky (there just isn't really any insulation in the storage compartments and even inside the motor home it's pretty limited). Personally, I wouldn't run the LPG furnace in a unit that I wasn't living in just because I'd be concerned about the flame (although I don't think it's really an issue) but I think in a cold spell, your LPG tank might last a week. There's also a risk that snow builds up on your furnace exhaust - if that's the case, I'm not sure if your furnace would light up again.