I always leave for a trip with one bottle completely full. I've started leaving both bottles open with the manual switch towards the partial tank. There's absolutely no way I'll run through a 20 lb. bottle in a few days so I just check the indicator when I hitch up. If it's red, I know one bottle is empty and the other is now a partial bottle. I get home, switch the manual to the other tank and go fill the empty. Rinse and repeat.
2012 Chevy Tahoe LTZ - HD tow package
2017 Rockwood 2703WS Emerald Edition