I appreciate you actually trying. A "negative" result is still valuable.

What I don't like about the article is that small fan have to spin fast (= noise) to generate enough flow. I'd much rather use a 80 mm fan, slowed way down, but I suppose I'd had to roll my own case for that. Better still, wait for someone to start offering this (or maybe this: http://blog.flirc.tv/index.php/2019/06/24/new-pi-4-cases/)