Since we are talking mirrors.  Both of my external {power} mirrors on the Hyena ('88 WBX Westfalia) are severely delaminated with only an orange-sized filed of vision left in each.   Needless to say, the will not pass the motor vehicle inspection (MVI).

I have spoked with a local glass shop who can cut new mirrors, but are loath to enter into the mirror housing to replace the existing glass and are actually proposing to glue the new mirror overtop of the old.  This strikes me as possibly asking for future trouble with the power mirror mechanism.   

Is it a big job to replace the glass in one of these mirrors?   Unlike my Jettas, the mirror cowling does not appear to disassemble which seems to indicate it will be necessary to take the door apart (at least partially) to free the internals of the mirror?