They are awesome fans - no doubt about that. Also, their customer service for after the sale is legendary as well. We have two of them in this rig, and have had them in all of the past ones as well.
The best system for us is to turn on the bathroom vent and open a back window when sleeping. That keeps a nice cross breeze for cooling. They also work great in the evening when it is cooling down - opening the windows and cranking the vents gets that hot air out pretty well.
I would recommend getting the reversible models - blows and sucks. (that doesn't sound right, but you know what I mean). Also, consider the covers for them because you usually need the fans the most when it is raining outside. Just how it works out.
Not sure that you can count on using to "cool" your rig, as it just moves ambient air. It WILL get the air moving inside the rig, and that is usually what is needed if you are in mild weather.
Easy to install if there is already power running to the opening. If you have to cut the opening yourself, let me know so I can come watch!!
--kev