Remote switch on 20m cable a good idea?

I have a timing system which measures the time between two points when a car is detected at the start and finish. Normally they communicate over Wi-Fi but someone asked me to make a wired version. The units would be placed about 20m from one another.

If I can get away with attaching both sensors to one micro controller (the sensors provide a simple open close signal which I'm getting from the GPIO pin with an interrupt attached to it) that'd be ideal but I'm concerned if the signal across a regular cable would be susceptible to noise. It's used on a racetrack, There's usually sound equipment as well as people using radios on site.

I'm thinking 2 microcontrollers with a proper R232 or similar communication layer would be a better approach but I was just wondering if the simpler solution might work