Have a 12' 1500 SLT with black interior and at night I can't tell the cup-holder (which is always open with a cup of coffee in it) from the rest of the dash.
As I said, it's ALWAYS open with a cup of something, coins and my phone in one of the 3 holes. I wouldn't think it would be too hard to mount some small light of some sort to the back edge of the holder itself or tucked back up in the space it pulls down from in the dash.
I'm guessing it could be wired to something like the power outlet that's only on when the key is on. But I know just enough about wiring to be very dangerous with it.
Thanks for any suggestions - that are physically possible.