My Monaco had a slightly larger tank, but I never bothered to make sure I was topped off every trip. But I would make sure I was full after first use out of winter storage, depending on propane use during spring I might have had it topped off on my way home from a memorial day trip, if not I always topped off at the July 4th trip because I would be down to a half tank by then. My next top off would usually be just before my last two camping weekends in November before I winterized. If I did not top off then, I would always top off heading to my Florida vacation to ensure I had enough while I was at my campground for 2 weeks.
With the 5th wheel it is a little easier, but I need to remember I only carry 14 gallons now, not 26.
You are correct, many retail/strip mall locations are going exchange only. But I have never had an issue finding someone to refill, usually my local tractor supply, uhaul, and any place that isnt at a strip mall continues to fill bottles while all the strip mall locations have cozied up to the exchanges.