Yes cool down the fridge a day or two before the trip. Norcold says it needs that to keep things frozen; it is not designed to freeze things from warm.
You get advice not to run your propane while driving. Some people pooh-pooh that advice. Some just say turn it off when at a gas station, but otherwise no problem. Some say theirs won't stay lit while the wind blows out the flame.
We don't have it on while driving and find that things stay cold enough till we get there and can turn on the propane or shore power. Might be different if it is 100F out, don't know.
Some arrange for an inverter to run the fridge while driving so they don't have the possible propane situation.
