And regarding the original topic, I intend doing a video soon on Kamm tails.
The latest
SAE paper* on the topic (2020 published! - very rare to find new stuff published on the original low drag shapes), basically debunks so-called Kamm tails as a way to low drag.
(*I found the paper through a reference that Aerohead made to it here - thanks very much for that.)
The SAE guards their copyright fiercely but there is no copyright on facts, so I will be able to summarise the paper in my own words without issues. (But not use any of their diagrams, unfortunately.)