I can't answer your question.
But I have been thinking what to do on my own build to protect the ballscrews. I was thinking of using some kind of broom material in two strips if I can find it. Like the bristles of a broom, mounted as a shield with the ballnut housing extension parting the broom bristles behind the Z axis.
I don't know if I can find said broom bristles.
But perhaps that's another option for you if they can be found.