I'd like to make the MCU changed to a Division Chief, or Watch Commander. The idea follows the US's National Incident Management System (NIMS) that span of control is usually best managed by 4-6 personnel or units. So a Battalion is required for 4-6 stations, while a Division/Watch Command covers 4-6 Battalions. The game is already set up this way, it's just a matter of changing the name.
I would then create a separate unit as a Command Van/Truck or Communications Truck, but there would only be a requirement of 1 per department. There are few departments that I know of, that would ever have more than 1 command truck...FDNY and LAcoFD being just a few examples. Also, any mission that required a Command Van could not spawn while another event that requires a command van is currently dispatched.