I've had this thought myself. It's a big problem for me when grading as you are contantly looking back and down, a real pain in the neck if you will.....
HA
I could see where it would have to disconnect when mowing or for sure it would get snaped off by a tree limb or shrub.
If you could quickly disconnect it you could use a much bigger mirror. I think the mirror would have to large to be of good use.