Slide topper noise

I'm living in my first 5er. I have a 2004 Montana with slide toppers. During windy nights, I can hear the topper on my largest slide out flapping and it sounds like someone is slapping the roof of the slideout. The bed and the kitchen slideout toppers don't make noise so it appears to have something to do with the size of the slide. I checked the tension and it pulls the vinyl topper pretty tight but the wind is still able to "flap it". It also collects water in the middle. It doesn't seem like I can tighten the springs that hold it taut AND if I could it seems like that would be putting too much strain on the vinyl.

Any advice?
I'm considering making a contraption with PVC pipe and those floating foam tube things to sort of "tent up" the topper.