We had a customer have a similar setup with only 2 ESX systems (when the AUX and VIP was not able to see each other then issues happened when they upgraded to the latest build 5626), we did not certify it for your setup. But you will need to make sure that the AUX and Ping nodes will be able to communicate or it wont work. If you are going to use this type of setup please wait until the next release as the Aux ports assigned with the VIP currently with the 5626 version will not work. Next release is ETA near the end of the month or sooner. But even so I would strongly test before you implement in your production and test with pulling a NIC and using the Failover.