26:th-Jul-2016, 20:50:02
I would get some black fablon, cut it to the same shape as the cover, only slightly larger all around. Dry fit it to the window so you can make the necessary cutouts for the mirror plate etc, then peel off the backing paper and fit to the window. I would then use either 3M tape or some glue to stick the cover plate to the fablon and then fit the mirror, wiring and cover.