I haven't taken the time to look into it, but I've wondered if certain aspects that appear on the center screen can be snooped from CAN (specifically AP state no nag, small nag, big nag pending AP abort for example, as well as turn signal status).
I don't need to know my speed, but perhaps an additional state of detecting speed greater than the determined speed limit...
Then just put a small strip of RGB 5-10 leds in the vent behind the steering wheel where you can't see them when off (I saw someone add their own "ambient lighting" by putting an LED strip down the entire vent, which gave me this idea) and then use colors and position to indicate status. Outside ends of the strip blinking for turn signals, center color to indicate AP state or overspeed etc...
Would be subtle and provide some feedback without even having to look at it, just having it in the field of view.