Refrigerator use in pop-up

For us, the fridge is too small to totally eliminate a cooler as well. We use it for things not super temp sensitive (condiments, cheese, eggs), veggies and beverages. We find that we can leave it set to max without freezing overnight if we add the next day's warm beverage cans before bed at night. This also prevents us from ever adding anything warm to the cooler, so ice lasts 3 days in there even in summer.

Our Sun Valley floor plan allows fridge access with the top down, so I clear out the fridge at home without popping up again. I never bother to load the fridge at home before a trip.

Afterwards, a quick wipe down of fridge interior and leave a rag on the floor to prevent fridge door closing. The flimsy clip busted MANY years ago...

We use our fridge even for the return trip home so it's actually in use. I can access the fridge when when the PUP is closed up although I do have to crank the roof up a few inches to open the exterior door.
I then leave it propped open to dry out.

As others have said, if you're going to empty it at the campsite, then just prop the door open.

The latch that holds our fridge closed is also designed to hold it slightly open (1/4 inch). That is all that is needed to keep it dry inside while in storage.

All we've ever done is clean it with vinegar (full strength), wiping everything down. Then, spritz the entire inside, again, with full-strength vinegar and keep the door open just a quarter inch. With the second spritzing, do not wipe. Vinegar is a natural disinfectant.
That's it. If you have a moisture issue, then any of the products that soak up moisture can be used and left in the fridge.

If I'm camping close to home, I usually empty mine before I leave the camp site and put the food in a cooler, then prop the door open slightly. The fridge is beneath the sink/stove top which swings down in front of the fridge, so not a lot of room to open the door, but at least it is open and doesn't get all funky in side.

If on a long trip, I'll leave everything in the fridge, then pop back up when I get home, empty out the fridge, then prop open door before closing up.