WRT mirrors. My go to for all my bikes is the Take a Look mirror https://amzn.to/2XcOFBY that fits on your glasses  frame, ( you can fit it on almost all glass frames except for the wire rim type.
Approx  $12
It's easily adjustable, stays put ( again on you sunglass or eyeglass frame , not that well on your helmet, and give great, convenient  rear view vision.

Bike Peddler Take A Look Cycling Eyeglass Mirror
by Bike Peddler
4.1 out of 5 stars    2,045 ratings | 58 answered questions
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