This past December, we found ourselves in Colorado Springs, CO over Christmas and New Years. Temps at night were dropping into single digits. To help offset the propane usage we placed an electric heater in the basement and used the fireplace. A heated water hose of course is a must in those conditions.
One tank of propane would last about 2 to 3 days.
This kept us from any frozen pipes while several folks around us had issues.
I have looked at the 'cheap heat' system in the past and thought it "sounded" like a good option. But I could spend a bunch of money if I got ALL the good options out there for my rig.