Dometic actually did some engineering on refrigerator cooling improvements and they have a design called the Innovation Ventilator System. They recommend that RV manufacturers follow those designs when installing a refrigerator, especially in areas where top venting isn't possible. Unfortunately many (most?) RV manufacturers have chosen to ignore those designs.
I also did a science fair project on the Domentic installed in my Class B following Dometic's design guidelines. I also tried a few other things and learned quite a bit about what limits performance on these refrigerators. If anyone is interested, my findings can be found at:
Chillin' with Bob