Some years ago they were designated "Mike Delta" and had a bit more of an on-road prescence. Then in the ensuing years there were a few deck chair shuffles and name changes as the statewide team structure developed.
The latest is having a State Duty Manager residing in the EOC who is the magnet for all things "pear shaped" - with various team leaders (Lima Whiskey etc) doing the legwork on the road. You may contact the SDM for things like jambing your ambulance in the Macca's drive thru, if you had a disagreement with the nurse at the local pre-mortuary facility - and any other trifling matter that you feel inclined. They also look after immediate staffing/workload issues, crib break complaints/coordination etc etc.
To my knowledge they would not leave their post to drive a command vehicle. There was one particular SDM who was driving the "Command 2" checkered Kombi, but this seemed to be more like his personal ride (connected to other non SDM related projects) than anything to do with being State Duty Manager
These are just my observations from the road - and these are often quite different to how things really work, so please feel free to correct where my view differs from the SDM Duty Statement