I think the Group Officer positions could be dissolved, instead favouring for: Brigade Captains and Brigade Duty Officers (typically a Yellow hat) to assume the role of a Red Hat when required. So say if you have 5 Brigades...you have 10 possible people who can run as a Group Officer...When Required. (to Assume IC, Ops, Div Comm, Sector Command positions during jobs).
A group duty officer could be run very much like the DSC state position. He would have the Main group car. and at any time the duty officer role would change while BC's and BDO's would get notified.
Any further group cars could then be strategically placed through out groups, in stations, to have a driver send the car to the job....change over the crew leader of a specific appliance, so that the "group officer" can run his on-scene role from a command vehicle.
***this is only a rough idea of an idea