[QUADRIFOGLIO VERDE]

Any thoughts on whether it will mess with the ignition somehow to sit for awhile in the ACC setting?

No the ignition is only activated when the key moves to start or AVV (avviamento in Italian). The middle position is the Accessory

 

[QUADRIFOGLIO VERDE]

BTW, MAR stands for Marcia, or gear, as that is the position the key resides in when the car is in gear and driving