You do not need 4 management servers to have a one management to cluster correlation unless there is a separation of business involved.
You may be better off restructuring your management to have multiple policy packages on 2 Management servers in HA and use two remaining servers as extra log server and SmartEvent.
Additionally, if you are trying to redo your management and logging infrastructure, consider that R77.30 is scheduled for deprecation in a few months. Consider migrating to R80.30 while redesigning management and logging.
P.S. If your management is on virtual machines, you are not limited in the size of the storage for the log servers.