Always good to see a DIY project. Very nice!
BTW, regarding the front door speaker adapter, the speaker is actually meant to be mounted to the other side of the adapter so that the speaker is sandwiched between the adapter and the door panel. Your speaker is very shallow so it doesn't matter for you but if you were using something deeper, the only way it would fit would be to mount it the other way. I only used the foam gasketing on the door panel side to ensure a tight seal between the speaker/adapter assembly and the door panel.