Nope, this is not the problem I am having.
I don't want to poll all IAPs based on information returned from the VC. I want to poll the VC itself. I can very easily poll the IAP address of the VC (or any other IAP if I wanted to). But these IPs changes from time to time. I cannot poll the virtual address itself.
NAT is really irrelevant to this problem. I only mentioned it as an illustration of one reason why it is difficult to deal with dynamic IP addressing on IAPs if there was no consistent IP to the poll the VC on - because of the problem of maintaining static port forwarding for a changing IP.
The latest software appears to have a 'preferred master' option to increase your chances of finding the current VC however this is not really a solution. An ideal solution would be for the VC to listen to snmp on it's virtual address.