You have at least achieved the objective of reducing the towing package.
I have a 24 foot class C that has been very good for driving and parking in the outskirts of lots. Nice size - my wife and I seem to get along OK inside during bad weather times. Normally we do everything we can outside as we started as tent campers.
Propane should not be a problem. A 20-pound tank only holds about 5 gallons anyway so just more than double your experience with changing tanks.
I have only a 9 gal. tank. Using the refrig full time, it will last at least a week. Since the refrig won't hold a week of food, you will probably have to drive somewhere before you need to worry about refill. I don't generally use heat continuously so that could reduce the refill time. However, again I think you will be driving somewhere before the crisis hits (assuming you are not planning to tow).
I have often wished for the 20-pound tank as a backup and to avoid having to go to refill stations instead of trading tanks at a hardware store. But motorhomes have not yet advanced to that practical stage.