Putting an LED behind the tube instead of under it still makes a nice visible glow, and the place I'm looking at is easily accessible without disassembling anything, you could pop off the back plate and the LED is right there. This also means I don't have to choose the LED color while I'm assembling the tube board, I can have a bunch of tube boards made and ready to go then add the LED last, which I much prefer. I would just have to add pads for the LED right here:
View attachment 4257129
Do like.