Gunrunnerjohn installed one of their MARS simulators in my O Gauge SP Daylight loco and it works great. I don't know if they offer anything in red but it's worth a shot. Good luck.
Since the LED determines the color, you can have any color you like for the MARS light. ngineering.com even has a special version that is optimized for RED LED's, obviously due to the lower operating voltage. The N8031C version is for a Marslight with red LED