I have to agree with ScottG and disagree with the post about not putting one in your bedroom. You just need to do your homework on the fan noise issue.
The last time out we were at Silver Falls State Park in their old section and had issues with low voltage so quit using the AC with temps in the low 90,s for the weekend (we were pretty shaded with trees as well).
We have two Fantastic Vents, one in the bedroom of our 5er, the other near the rear kitchen in the LR area. Both are temp controlled and pretty quiet when on their lower speeds. Both can be reversed. Normally I use them with windows open some to pull cool air in and exhaust the fans out.. This time when going to bed I reversed the bedroom fan to pull in the night time air. Setting up these fans the way I did was one of the best mods I've spent on any trailer and would do again in a heart beat. I also believe we use the AC less overall.