Maybe you could try an adjustable aperture iris like:

https://shop.ahg-anschuetz.de/en/optics/shooting-glasses/353/ahg-flip-up-blinder-with-iris

They clip onto your glasses and you can adjust the position. Reducing the iris size (also adjustable) makes everything clearer but reduces the light getting through.

I have one but don't need to use it all that often at the range yet. I use it all the time to read my old vernier caliper - it has 0.1mm markings and my reading glasses don't quite make it clear enough.