When driving my class c with the windows down, there is a lot of wind noise and wind buffeting due to the design of the class c itself, just wondering if anyone has had success using the window " vent...
You should be able to relieve "wind buffeting" by opening any window or vent in the house.
A class C with a frontal over-hang will have more wind noise than a B+ because air gets trapped against the windshield, then whips around to the sides with greater force. The van side window shields (or vent visors as you call them) might help with some of that. One certain issue with van side window shields is that they take away from your sightseeing views and passenger-side picture-taking.