Cisco Virtual Wireless Controller and Vmware Promiscuous mode

I have read every post and guide in regards to deployment of cisco vWLC. Only part I dont understand is that they make it a huge point that promiscuous mode must be enabled on the vSwitch or in my case port group.

Cisco vWLC deployment

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I dont have any free NICS on my ESXi hosts for a new vswitch. Also I dont want to enable promiscuous on a new port group on one of my existing vSwitchs since it will allow it to see all traffic in that vswitch (much unrelated wireless traffic).

I was wondering if anyone has run a similar configuration or has a recommendation?

(i wont be using the service port)

Edit: Just to be clear, if I could get more NICS i would. Everything is taken, including expansion slots