I have the same problem with the long deflectors under the car, and the wind noise has been driving me crazy. I want to give a huge thank you to haedgy!! After reading this post yesterday I followed haedgy's advice and fashioned some closed cell foam into doughnut shapes about ~1.5" thick. I opened up one side of each panel (the exhaust pipe side) so I could place the foam in between the chassis and the panel. With a slice on one side of the foam doughnut I was able to "hug" them around each of the 6 large round clips (as shown in haedgy's 2nd picture).
Once this was all finished there was no more rattle when I tapped my fingers on the panels, and best of all no more wind noise above 40mph!!!
My question is does Ford have a true fix for this? I can't locate a service bulletin or recall. I'm quite hesitant to bring my Edge into the dealer only to have them replace it with the same faulty part, and then have to do this whole foam fix again in another ~15k miles when the rattle starts again. Not to mention I'll be outside of warranty by then. Right now I'm more than okay with the foam doughnut fix.