The GEO Method and Space Heaters - Thoughts?

For heat, my favorite method these days on a trip like that would be to stay at a place with electrical hookups and use a small portable electric heater. Or use a propane heater and turn it off when going to bed. At the temperatures you describe, you and your RV plumbing won't freeze. Good long undies and lots of blankets and sometimes even a knit hat take care of night heat needs safely.

I never run either propane or electric heaters while I am asleep.

Have a great trip!