Thanks for the information in this thread.
I just wanted to point out that some manufacturers are now putting the side vent on even when the fridge is not in the slide.
I used to be a quality snob but I needed an 18' garage toy hauler and had to do a little bottom feeding. My unit has the side upper vent but I have no slides. I have noticed some concerning heat periodically at the side of the enclosure next to the stovetop. One time it liquefied a jar of coconut oil (normally solid) that was sitting there. Before my next trip I plan to ensure the installation conforms to the manual and perhaps install some fans. I have a Norcold N811VFRW6.
I found this link informative:
http://www.fridge-and-solar.net/fridge_vent.htm