The end of the handlebar route sounds like the right way to go for me.

The glasses or helmet mount sounds like a non-starter. I also have this vision of swatting the whole works off my head when the bugs are out in the summer.

I lost a pair of prescription sunglasses in the lake once when I was fishing. My wife hauled in a pike that was flopping like crazy. The fish smacked me in the face, 3 treble barbed hooks on the plug whistled past my ear and plunk ! There go my glasses !

I've kept my glasses on a chain or a string around my neck ever since then.