Mounting an SG over the rearview mirror wouldn't work well for me either~! I have a problem with the mirror blocking my right forward view and have developed the habit of looking
over the mirror to make sure traffic is clear. The closest call I had before doing this was merging into a lane at a "Y" - right in front of another car~!

Luckily he saw me in time to slow down and let me in front. I thought seriously about removing the mirror totally and am still looking for an alternate mount that would let it be positioned up higher.