While your inventiveness is certainly noted, there's this:
It's a Problem Solvers product. Has the additional benefit (to me) of getting the light lower, where the pavement profile is better lit up, and keeping it out of others' eyes (even if, like wearing a mask, the flash-holes won't do it for me). Does look pretty dorky without a light on it, but I use a USB rechargeable (Urban 500), and don't leave stuff on that can be easily palmed while I'm looking the other way. I do carry a regular QR nut too, just in case the mount disappears.
Would your spouse be averse to one of those Velogical bottle dynamos? They look pretty slick to me, and I'm tempted.