Oh okay so you don't even have any sound insulation on the other side of the mic. I was reading that there are several other owners of Ford vehicles like the Edge, Explorer, Mustang, etc that are griping of the exact same issue we have. One guy actually dropped the mic down from his overhead and let it dangle just to test if it made any difference being away from the roof. It was interesting to read that he reported it made no improvement whatsoever that the mic was picking up cabin noise despite if the mic was mounted anywhere else in the car.
So much for the idea of relocating the mic and also there may really be no improvement with insulation or sound deading material over the mic.