I have to say we just re-filled the propane on a whim. Good thing we did. We had to fill our 30 pound tank (7 gallons) with 6.8 gallons of propane two days ago. Which means we only made it 61 days with last propane fill. Which is about 21 day less than I was thinking with our last fill. Which means right now we are averaging about 10.8 days per gallon. On the last tank we averaged only about 8.7 days a gallon.

All of which means on the new trailer, which will have a 20 pound tank which is about 4.7 gallons. We will need to refill about every 6 weeks. I would say we should fill once a month if we have only one tank.