You could light up the 'monitor area' from above, with an LED from above. I have 3mm and 5mm ultraviolet LEDs. If you want, I can send you a small battery holder for a button cell battery with resistor two wires soldered to either the 3mm or 5mm UV-LED. You can drill a 3/5mm hole above the 'monitor' and push the LED inside to light the graphics
All you have to do is place the battery holder in the base of the cab and make it accessible for switching on and replacing the battery if necessary.