I installed a rubber pad on both sides of the canopy to help absorb the vibration. The pads go in between the metal plate and the canopy. One on each side sandwiched in between. To be clear, I put the plate, rubber pad, canopy, rubber pad and then the second plate. Bolted it all together and that gave me a flat mounting surface for the mirror mounting button. I used JB Weld to mount the button to the inside metal plate. Wait a full day before mounting the mirror on the mount button.
Hope this helps you out.
Hope this helps you out.