Great job on the install. I have been brainstorming on how/where to mount my sub. I would love to mount it on the rear deck like you did.
To fix ur liences plate - just un screw n shove a napkin behind it is it is tight when screwed back on. Cheapest sound deadening on the planet and works everytime.
I came up with that one long time ago. It always makes me laugh when I hear a plate rattling when the fix couldn't b easier.
Keep enjoying ur tunes.