I don't understand the question? >> Why?
If I knew that I'd probably understand.
I went back to your most click-bait title: There is no magic in a Kamm tail!
I remembered it as conflating Kamm-back and Kamm-tail. At
5:35 You have the red, blue and not-green lines. A Kamm-
back is a field expedient fix for the area between red and blue lines. I view it as a boxed cavity.
Since I'm minus a Kamm-back and pressure pucks and tubing, I can't establish the differential between the inner and outer face of a Kamm-back. I hope that answers your question.