Rearview mirror problem.

Now that I have "More Power" my 2.1L - 84 Westy has a new issue. since I can
not hit 80MPH with little effort; the wind causes my mirrors to fold-in at
high speed.

Sure the easy fix is to drive slower, or try to tighten the bolt / spring
even more (I think I've got it as tight as I can get it), but I wondered if
any of you have a better solution.

Thanks,

Jack R.

84 Westy, with a 91 synco 2.1 motor