I'm trying to come up with some neat lighting
This really isn't about your sidelites, but I have been thinking about this for some time, the problem being what loco, and the Phantom is the perfect one for it. I recently bought a saber saw with one of those laser pointers that draws a red line out ahead of its cutting path. It not only really helps you cut straight, but it looks cool.
Something like that, a bright red line shooting out and pointing down the track from the Phantom's nose every time the horn is blown, would be cool, in a futuristic loco. Not sure where you get an inexpensive laser that draws a line rather than a dot, but . . .