Long time ago, in NL, I got a thin tube of reflective plastic, with a wire down the middle,
that formed a ring around amongst the spokes, inside the rim, unlike the reflective ring on tires,
its far enough up from the brake grime and general dirt to be clean & visible, better..

adding a few LEDs to that sort of ring , would be a simple improvement.
It could be induction powered, like Reelights