I used a set of aftermarket fairing mirrors until I broke one. They were a waste of $22.00. I could never get them adjusted so I could actually see anything behind me.
Aftermarket fairing mount mirrors are often reported as being inferior on several counts.
I questioned using them but in the end I didn't. The best thing you can do is get real motorcycle mirrors. None of that aftermarket crap. Only stock mirrors seem to have stock quality. Everything else vibrates like crazy.