Furnace is the big user of propane.
In the early spring/late fall when we run the furnace a lot and are don't have elec hookups, 7gal propane will last a 4-5 night trip. In the summer, when the furnace never runs, a 7gal bottle will last 20+ nights.
I would have dual tanks for peace of mind.
2007 Chevy Duramax LMM/Allison
2012 Jay Flight 29QBH
2012 Jay Flight 26BH (Sold)