I have completely removed the back cover plastic rain cup, and will be installing foam baffles to make up for it.
I have studied the door, and to increase the inner diameter of the front speaker orifice, requires a bit more major surgery. The door hole as is now, is nice and structurally stiff, if I go into it, I will lose that and have a thin single sheet of plastic to mount the speaker on.. and I have no garage, wood router, or set up to go into it...
I could use my spacer ring as a guide, and try to dremel it out, and maybe mount the spacer ring underneath the plastic... but there is that bottom metal beam in there too...
Sorry, once and Engineer... always and Engineer...