have you considered the BMW hard wind deflector?
Like this one on my car:
It does not block the view through the mirror too badly although I grant you, they are pricey (around $500 or more maybe these days) and getting hard to find. the kit comes with new roll bar covers, the center mesh panel, two inserts for the space in the roll bars, mounting rails for the roll bars and a set of trunk lid mounts so you can remove the mesh center panel and stow it on the underside of the trunk lid.