Because of my elevated position in cars, rear view mirrors typically create huge blind spots for me. I used to duck or move to the side to see around the mirror, but I got tired of the inconvenience and it probably wasn’t safe either. I detached the mirror from its normal position and mounted it to the plastic counsel on the roof. Four drilled holes and four rivets did the trick.
I got a spare rear view mirror off ebay that can be suction cupped to the window for when others drive my car. In the second picture below, the spare mirror is located at approximately the original mirror position. If you look carefully, you can see a car that is about to pass through my blind spot.