There are only Humphris Arms at £500+ I believe for 2. For the NME Kit Cars.If such a part exists for the micra it would be an easy fix, it might be worth asking Matt Humphries or other micra parts specialists if something is available or which other makes or models have the same taper, I was trying to imagine some sort of screw on extender but there's not much room available and I think it would be weak.
I was just looking and it appears there are no other models that use the Micra ball joint, so it might be a tough search.
I was developing one a while ago that rid the arm of the angle of the ball joint. Meaning you'd not affect roll centre until the passes the horizontal point which would be the limit anyway
More favourably though is correcting bump steer as they suffer from it a fair even with minor changes