If you call the Parts Express hotline and ask someone nicely, they might be able to measure the thickness of the flange for you.
If you can wait until late tomorrow evening, ( 10 pm or so ) I may be able to take a measurement of the thickness of the exterior flange, IIRC it's around 1/8th inch, and the port flange is textured on the outside. ( flat portion ) I can also measure the outer diameter for you. Honestly, I would not recess it, as it's not very thick.
"What the heck was that crashing noise?" Me: "oh, just tossed the shampoo bottles off the shelf on the opposite side of the house. "