Was able to work more on this last night. Finished up a prototype baffle for the dash. Learned some things doing so and will incorporate what I learned into the baffles I will actually use for a better fit.
Need to decide a way to secure the baffle to the dash. Was considering the 3m double sided tape that I've been using for holding down templates when routing. It's actually rated to hold up to 5lbs per linear inch, removes clean without residue and I feel would seal & act as a decoupler also. It is a little thick though, about 1/16", and I need all the height clearance I can get to get the stock grill to fit. Maybe a couple of machine screws and either riv-nuts or hex nuts from the bottom. Riv-nuts would require a clearance bore on the back side of the baffle. Would still need something to seal and decouple the baffle in either case... possibly use some clear silicone
Here's the baffle by itself
Had to use this router bit to cut relief slots on the ID of the baffle. These Morel mids mount with spring clips that will snap into these reliefs. Baffle is upside down in this photo:
Here is the mid snapped in place. Need to decide on how to seal the speaker to the baffle... maybe just a thin bead of clear silicone.