We have a 2" on ours. Can't be completely shut when we leave it on the beds so we just roll it up and store in when traveling.
If you camp in the heat, the bunk ends will get really warm. There are a couple of ways to deal with this.
#1. Get a large roll of Reflectix at HD or Lowes and cut to fit between the zip down window flaps and the screen portion of the bunk ends.
#2 Get some bunk covers from www.popupgizmos.com
These two things will make the summer more bearable.
Courage is the feeling you have right before you fully understand the situation