I finished installing some addressable LEDs into SM. There is a set under the backbox and along the apron, and are tied into the gameplay using a Pinduino. I think it came out pretty well (and the end game sequence is nice at 7:42).
If anyone wants the code: https://github.com/elyons/professor_pinball_pinduino_sketches/tree/master/SM-Apron-Back