Building my tear and will have a window AC unit permanently installed in the interior center. I have not decided if I will offset it to one side or center it. If I center it I will exhaust it to the roof, if I offset it I will run the exhaust to that side.
What I cant figure out of find something that looks good is an exterior vent. I've thought of using a marine deck plate that I would have to unscrew when I get to camp. Or use something like this (3" is a tad to small for a AC exhaust though)
http://www.etrailer.com/Enclosed-Traile ... fgod4vUKIA
Anyway, if anyone has an idea I would love to hear it.