Most of us run with the propane on. That said, if you do decide to turn it off, I would suggest that you make yourself a little reminder card or something that you can put on the steering wheel so you don't forget to turn it back on. We have one that is business card size, laminated, and with an orange ribbon. It says Turn Refrigerator On and we use it any time we have to turn off the fridge because we can't park on the level, filling fuel, or when taking a ferry. We keep it in a small drawer right next to the driver so it's easy to use.
Incidentally we have others that say Turn Antennas Down and Remove Foam from Slides (we put swimming "noodles" on the slides to prevent head injuries).
ArdraF