5th wheel is stored at a storage lot, so we put the fridge on propane as soon as we pick it up, drive it home, load up with food/drink (and a couple of ice-packs if it's not cold enough yet), and then leave it running while driving to campsite.
On our old pop-up, which was kept in the garage, we used to just hookup power the night before and run the fridge on electric (didn't want it running on propane in the garage), and then fill up before leaving (with some frozen goods in the fridge to help keep it cold while driving). We just disconnected before leaving home and let the cold stuff inside the fridge keep it cold.
2015 Rockwood Signature UltraLite 8281WS
2016 Ford F-250 Lariat CrewCab, 4x4, 6.2L V8