I installed 12v computer fan at rear of my 2006 Jayco TT's fridge as well. Simple plastic pull ties to hold it in place. Added manual switch and inline 12V fuse. Works great. Glad to read this behind the fridge extra cooling fan is now factory build in many newer year models.
Note: If installing your own fan, do install a manual off/on switch as well. Thus, turning off at night - when the wife's elephant ears wants to sleep. LOL!!! Happy wife = happy life!!!