Bondo wouldn't work[?] Oh well, if you don't use Bondo, you can use any quality heavy-duty glue. I don't foresee you having to move them at some time once you get them initially adjusted, so if that seems to be your last bet (which it does seem) then that would suffice. I have never had to readjust my mirrors since I got my bike. I wouldn't suggest sticky goop, either. That would get all gummed up and become messy. Besides, that probably wouldn't do the trick. It would just take a bit longer for your mirrors to become unadjusted.