Our 2003 Southwind has a lot of wind noise when driving around 65 mph. It sounds like it is coming from over the windshield area, rather than the side windows. We had a 2001 Southwind that was extreme...
We had similar situation, and discovered the "weep" slots plugs along the window frame had been dislodged. After obtain and inserting the plugs - problem solved. Hope this solves your situation.