I don't quite understand the extreme propane conservation measures.
Without considering heat, regular cooking, 24-7 fridge on LP and hot water as needed for dishes and bathing, 2- 20lb bottles literally would last an entire summer possibly longer.
I've got 30# bottles and only pack one in the summer, even on extended trips.
Extreme cold, 3 nights at close to 0F and day times up around freezing, used 1 30lb bottle for a 4 day trip with no regard for conservation of heat really (except when the batteries went dead middle of the night, lol).
Summer camping, 4 weeks, mostly no hookups, fridge, hot water and cooking, less than 1/2 of a 30lb bottle.
4 weeks fall camping (at work), cook 1 meal a day, lots of hot water (used it like it was free because I was in the woods and could dump the gray water at will, but had a water hookup), fridge on LP, heat on every night, temps near freezing outside used exactly 1 30lb bottle.
Heat uses alot of propane, the rest of the camper features use very little.