Well, I removed the speaker (drivers door), and it ain't working, and probably never will again, but not to worry, they're all getting replaced in a couple of weeks anyway!
Whilst I had the door card off, and the speaker removed, it let me check the mounting depth available, so here you go.
To mount on the metalwork in place of the original, your maximum depth to miss the window is only 50mm.
To surface mount on the re-fitted door card however, this increases to 75mm.
Good! I can still go for the Vibe Blackair 6 components then, best get the wife to order them in time for fathers day!