Played around with some different mirror configurations over the last months and now have a setup I really like.
Mirror heads from https://mirrycle.com/products/mirrycle-mirror-holder-with-mirror are cheap and give a wide (enough) view.
I threaded them to accept an M8 rod, bent the rod to my liking and covered it with black heat shrink.
Mounted with black washers & nuts. Really nice view of the road behind with (almost) no vibration.
Very minimalistic & stable compared to the other options I tried. Works with my red & black theme with very little shiny stuff.

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