Is there any type of curved baffle from the fridge to the top of the vent edge? Before my AS I had a Casita that had the 4cu/ft Dometic with the side vents but in the Casita the top of the fridge was just below the top of the upper vent. There was fiberglass sheet that was screwed in to deflect the hot air to the vent. Many of us removed the fiberglass baffle and behind it stuffed fiberglass insulation in the void between the top of the fridge and the inside cabinetry. Some would fabricate a aluminum baffle from the fridge to the upper lip of the top vent filling l the void above it with fiberglass insulation or gluing some to the back of the baffle. I decide to use Reflectix silver coated insulating material or radiant barrier. It comes in a small roll at any of the big home improvement stores. I used two sided tape and some of the silver aluminum tape to seal it between the top of the fridge and the vent lip. I had a fan in the fridge compartment and it was too noisy and didn't seem to help anyway so I never used it. There was a switch to turn it off.
Maybe you can rig up a Reflectex baffle in your AS. Post a photo of your upper fridge compartment.
RV fridges are a blessing as much as a PITA in hot weather. I've learned to keep beverages in an ice chest. Going in an out of a RV fridge when the interior temperatures are high just dumps all the cool air out fast. Then it takes hours to recover back to the 37 to 42 deg. Having the interior cool helps a lot but when towing the inside can get pretty hot during the summer. I find RV fridges don't perform as well in humidity either.
You could replace your one big fridge fan with a couple of quiet low amp fans. That might help the battery drainage and noise compared to the AS fan.
While boondocking a solar panel is essential. There are a number of portable panels available. Here is one a lot of Casita owners purchased
90 watt folding portable RV solar system - Economy Series | Off The Grid RV Solar StoreOff The Grid RV Solar Store
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