I found fantastic fans to be too loud and real annoying when you are sitting inside the RV and do not put out a lot of air.
The MaxAir Turbo Fan mounted OUTSIDE is IMHO the only way to go!
I installed 2 of them in my RV. Put one on in and the other on exhaust and stand back!
And because they are on the roof outside the RV you do not even hear them running. Ahhh.
*Be wary of the rain sensor lids. They close at the slightest hint of moisture. On my previous RV we came back to one hot RV on a sweltering day to find out both lids had closed shutting off the fans because of condensation from a neighboring campers RV air conditioner blowing across our rain sensor lids. :(
