Interesting write up. You mention cut a hole in the side to lift out the foam well with amp in it. I can't picture this - cut hole in side of what? Also, are you not concerned about air flow with the amp and the foam together? Back in the day (like 35 years ago) I was always a little bit over board on ease of cooling. Have a photo? Sure teh problem is I cannot picture it in my mind.
Only other comment is "it's not going to rattle your fillings." To me, this is a good thing. I was always after fidelity, not volume (even used fibre optics at one point for maximum fidelity in transmission) and rattling crap in the car is not what it is about for me. And rattling anything would be a no no (not to mention lining up for "get your free hearing aid test here!" a little early). The only thing that ever rattled was on a hot rod Camaro and at about 3/4 volume the pull down license plate (to expose the gas cap) would pop away from the back of the car about three inches or so on each, tight, well spaced, well placed, well defined hit. If I was in CA I'd drive over to check out your system, just for old times sake.
Keep up the good work, and preserve that hearing!