Thanks guys. I tried some black tape, but may try your suggestions because a little light still gets through.
Now for a marquee update.
Chopperthedog took my marque image and re sized it. (Thanks Chopper, I really appreciate it.)
I got it printed out yesterday at Office Depot. I took my pocket tape measure to insure it was the right size this time.
Chopperthedog made the black part 0.5" bigger in length and width. He also centered the image for me.
I wound up centering the printed marquees (I got two copies and doubled them) on one of the plexi glasses. I then trimmed the pics to fit the plexi with a razor knife.
It turned out very good this time.
Here is a pic of it mounted in the cab, led strip turned off, ambient light on, flash on cam on:

Got to remember to take a tape measure whenever I get something printed in the future.
And here it is with led strip full on, ambient light off, and flash off (You can see light bleeding around edges):

And here it is with black tape inside each side corner and led strip about 25% (this pic turned out blurred, not sure why):

And final pic is ambient light on, led at 25%, flash off. (Why is it blurred again? Im using a tripod):

Now I still do not like the characters looking green from the green led light. Im working out the details to light up these two areas with white or yellow LEDs.
More to follow.
Wiring update: Almost finished, just got to figure out how Im going to mount the PC power supply so it wont move when the cab is transported. That and a little tidying up with wire ties is all thats left, Im pretty sure.
Then it's on to the control panel.
This project is nearing the finish line, thanks everyone for your help, but dont close the help desk just yet.
Im open for ideas for side art.
Griffindod tossed out a couple ideas at the start of this project, but I think I would rather have something smaller for the sides, got to show off my fancy green paint! (I am cringing at the thought of getting side art printed out, let alone applying it.)