Some of this may be a re-post. When we bought the trailer in the summer of 2002 it had only the factory vent, but was wired for air-conditioning. We picked it up in Phoenix, hauled it to Camping World in Tucson and had the Coleman unit installed before we headed back to San Carlos. We had wanted the smaller unit (750 btu), but all they had was the larger in stock. That got us through the summer, but then there were times we really missed having a roof vent.
In the summer of 2003, while we were doing the other interior mods, we bought the Air Max and had it installed in Visalia, CA. We had gotten turned down on the installation because it was a new hole in the roof, but the guys in Visalia had put a roof vent in our old van so they were willing to give it a try.
The third mod was the "wine rack" built over the utensil cabinet. This was also done in 2003. We used 1/2 ply and made the shelves tall enough for wine bottles. We slipped athletic socks over them for the trip back to Mexico.