Temple Audio makes many lengths of LEDs…uses Cioks (9v) outlet. Peel and stick on the back…just trim off what you don't want…How do you all light the underside of your boards? LED's but I can't find any that are that short. I was thinking about getting a DC7 and using the USB port to power them.
https://www.sweetwater.com/store/search?s=Temple+audio+rgb