Went out camping this weekend with the temps reaching 95 degrees outside, our refrigerator could not keep up, never getting below 40 degrees. The freezer worked great, but when I checked the fridge, ...
Try to keep the fridge side of the RV away form the sun during the hottest part of the day if possible. There are also fans that can be retrofitted to move more air over the back side of the fridge to aid in the exchange of heat. You can also get some "blue ice" type things and freeze them. When the fridge isn't keeping up just move them from the freezer to the fridge.