There are so many ways to get around this. Think about a recent baseball “buzzer” scandal. Strap a vibration device or devices to an arm(s) or chest and if the crew wants to tell the driver to go high the vibration device on the right side vibrates and if low the left side. Or you could use lights on the dash direct where to go.
The vibration device has been contemplated by those that hate certain QB’s in football, too. For instance, how does a QB looking to his left regularly “sense” a guy about to hit him from the right and he consistently and magically ducks or steps forward at the last second to evade the hit???
Let’s be creative folks!