Nimbostratus
Is that because your VCenter setup won't let you do it? You can certainly add a third vlan to a third VMWare interface and use it for the HA vlan.
However I'd only do this if I needed to do connection or persistence/session mirroring. The way most ESX clusters are setup the BIG-IP's management port and data ports probably go out the same physical interface, so there's no extra redundancy for running network failover over both the management and dataplane interfaces. You can just use use the virtual management interface.
Paul
