Ah, I get you now,
how much room for the screen? can you extend the stem above the switch then widen.
Bit surprised you need them.... I guess you've not ridden anything modern lately? You can't see anything on the garbage fitted on most bikes nowadays.
The round mirrors are far better, the modern idea of silly sizes and shapes are pathetic. Stock old air cooled GS mirrors are some of the best out there... I have two other bikes and was the same with the LC GS, all need urgent replacement to make them safe to use on a public road