While I'm very new to the Starcraft, I have used an inside and outside fan on my other trailer (Casita). The inside fan helps by just circulating the cold air. it's a small compartment and stagnant air isn't helping with keeping things cold. it also helps prevent things on the bottom freezing.
The outside fan helps a lot as well. I changed from "oh dear, food is spoiling (50+)" to "no problems (40+)" when camping in 100 degree plus weather here in NM.
I would think trailers with the fridge on the slide would have the same problems that Casita has. Namely, instead of venting the hot air out of the top of the trailer, it goes out the side. If you look at Domestic's installation guides, that is the "least preferred" method.
My plan is to add fans to the outside of the fridge. I'll probably do like I did on the Casita, and use a couple of low amp draw computer fans. I'm thinking about putting them up under the roof vent - possibly strapped right to the fins. I doubt I'll do a thermistor - instead just put a switch somewhere. Time will tell