Extra insulation

First off no one tells you but you should insulate the roof vents if nothing else. This simple thing will help with the cooling more than you could imagine. And it is easy to do, you can purchase foil sided, roll insulation like in the following pictures from any home improvement store for about 25 dollars a roll. One roll will cover all the vents and most of the windows in an average size camper. And don't worry about how it looks, here in Florida you can tell if someone lives in their camper simply by looking for the extra insulation. Almost all the Rv's, even the luxury class A's have it on every window, door, vent, etc. There are many ways to install it. double sided tape, velcro tape, screws, nails, etc. And when the weather cools off in the fall you can always remove it. Although it doesn't look as nice as the large glass windows, it blocks out almost all the heat. Besides our camper was a 1993 with the louvered windows, and they never seal up completely. So with the addition of insulation we've stopped almost all the AC loss and kept out 95 percent of the heat. The AC does not run constantly anymore. I do recommend that you put it between the doors and screens. it looks better there.

Here is a picture of the door.

This is the roof vents, they are all done the same.

This is of one of the windows