DSQR, Try getting a pack of the felt buttons that go on the bottom of chairs, I had the same issue with the side rolldown curtain next to the driver seat, in the afternoon or early morning sun I like to pull down to just on top of the side view mirrors. The felt circle buttons (I'm talking the thick tan ones, not thin green) strategically placed, they work great, takes the banging noise completely out. Of course my go to fix for an issue like this is to turn up the stereo, but then the squawking from the passenger seat gets worse...
2015 Georgetown 364TS, '14 Fiesta 5 spd w/Tandem Tow Dolly HDXL 8x10, & EZGO Customized Cart
'16 - 51 days camping so far, 19 more min planned; '15 - 56 days
2011 Flagstaff V-Lite 30WFKS '14 - 24, '13 - 33, '12 - 36, '11 - 29, '10 - 23