Here is an installation diagram for the mirrors. They say it is left up to the installer on what to use for mounting. If it is screws used (as shown), then you could remove the mirror and try to beef up the area, maybe even re-fibreglass it. If they are machine threads (w/nuts) your only option is to access it from the inside.
I did get to learn about the 'rough adjustment" for the mirror here!
https://www.pacificrvmirrors.com/aboutus.asp Good luck
Stay cool
Thor Forums
