Allan Jude might be a viable candidate for some of the content, if he'd like to. Also, Dr. McKusick documented some of the internals in his living FreeBSD kern

Allan Jude might be a viable candidate for some of the content, if he'd like to. Also, Dr. McKusick documented some of the internals in his living FreeBSD kernel book, but as you said, this might be beyond Ars's scope. Though, I've seen some deep technical content on Ars, so why not give it a try.