one layer should be enough. gaps large enough to require 2 layers of CCF likely wont flex enough to cause a rattle/buzz. I would hit the door trim with some CLD if you haven't. I think it helps even when the doors are sealed up well.
I can do both no prob. And yeah was thinking of a little bit of CLD on the plastic panel as well. Was in the process of doing that on my glass cooktop since we don't have much counter space, and accidentally turned on the burner and melted my door ... a backup is on the way!