Before I replaced the reflector on my newly-painted cases, I was thinking why not wire in an LED marker light or maybe even a relay for a marker/turn signal (always on, flash on turn).



Yes it would require drilling the case and a waterproof passthrough & disconnect harness but I did that on my Wixom bags on my R-bike years ago, so certainly do-able.

Anyone know of a good LED source for something the right size?

These guys have a lot of LED stuff.  I'd think you could find something that works from them.

 https://www.superbrightleds.com/

I have bought all my instrument cluster and auxiliary LED's from them for about 10 years now.