Find the Rattles
A successful rattle treatment plan requires that you understand the culprits. A few likely candidates...
These and other mechanisms mounted to the top and bottom of the rear deck can be challenging.
This one has a decent jute decoupler to prevent rattles between the plastic trim panel and steel shelf.
I add a layer of 1/8″ CCF between the trim panel and sheet metal to tighten things up. For the trim panel above, I removed the stock jute and replaced it with 3/4" Hydrophobic Melamine Foam.
Rattles Against the Rear Window
Final issue to consider is the trim panel or third brake light making contact with the rear window.
I cut a 1″ wide strip of 1/8″ CCF and used a brush on contact cement to glue it first to the top edge and then wrap it around the back. When the trim panel is in the car, the CCF can’t be seen because there is a black band at the bottom of the glass.
Length * width for square inches. Divide by 240 for 25% coverage of that area. I'd double the number of CLD Tiles. Most rear decks have two layers of steel and you'll probably need a few for the trim panel. Square inches divided by 144 for the square feet of CCF or 3/4" Hydrophobic Melamine Foam you'll need.