Slightly off the path of this thread, I have a fix for the spring popping out where the arm pivots at the coach door. Can elaborate if you need that. But sorry, no repair hack for the mirror head itself. It seems the glass is available, not the cover.
That said, Velvac replaced mirror heads awhile ago because the white plastic was unstable and they yellowed. I don't know if they have any such campaign running now. Might be worth a call to check.
If God's Your Co-Pilot Move Over, jd
2003 Jayco Escapade 31A on 2002 Ford E450 V10 4R100 218" WB