This idea is completely dependant on what actually is available under the command certs.
But an idea for the vehicle side-grades would be a Command Module which can be fitted to the tank in place of the utility slot or something and enable the pilot access to the currently undisclosed command features while remaining inside of the vehicle. Much like using the CUD from planetside1 without having to leave the vehicle.
Such as revealing friendlies and enemies, call in artillery strikes, squad spawning and so on.
Maybe they could also introduce some tank/vehicle specific command certs for all those armour squads out there.
For visuals they could add antenna arrays ontop of the vehicle to make it even more of a primary target
