Refer question.. How long will it stay cold?

The door wont be opened at all once the food is packed in there... Its a bumper pull camper so everybody is up front in the tow vehicle. once she gets to where she is going then she can hook up to electric. We have done really well up to this point and not really had the need to use the gas. We do not have an oven (and havent needed to stove cook top) and anything we have needed to cook, we have used our little charcoal grill. We also have a little portable gas grill and the microwave. My work schedule is not going to allow me to fondle with the trailer before she leaves, other than hooking the trailer to the truck. But I will be reading up on the gas system soon. The guy at the dealership told us to never turn the gas on while the trailer was in transit so I never even thought of that as an option..Im glad to know that from here on out I will be able to cool my fridge down before we actually make it to the campsite.