Thanks for the link. I just looked at the bike again (now that I have it in my garage with access to plenty of tools. With those ideas, I think I'll be able to get something sorted out.
But a new pair of bar-end mirrors would open two mirror post holes...... and my LH mirror is floppy. I didn't see a way to tighten the mirror (round part) to the stem. Do you happen to know if that can be adjusted?