I have a spare crossbar trim piece and plan to do pretty much the same thing with a wide LED strip. My only fear is cutting the opening - not sure of the best method to accomplish the task.
I don't think my hands are steady enough to try it with a Dremel tool
Should I make a fixture to hold the trim piece and use a router with a small diameter bit? ...
... or make a fixture and attempt to run it through a vertical mill?