Put nylon inserts into the mounting holes and then use stainless screws to attach them using those clip-on caps to cover the screw heads. This is how I re-attached all the panels secured with plastic fasteners in the D2 and it completely eliminated all of the squeaks and rattles (from those panels).
While you're there I'd also put a layer of (inserting cheapest comparable material) RAAMmat BTX on the inside surface, it will reduce vibration/noise but it will also provide a waterproof seal. I'd also put a liquid seam-sealer into the gap between the skin and frame at the same time to keep it as dry as possible. The same people who sell RAAMmat also have an adhesive closed cell (likely neoprene) foam they call Ensolite that could be used over the damper to provide some additional sound-absorbing capacity.