I finished it (for now)! I finally got around to recording and putting together a sum of the best segments from all my practice in Environmental Station Alpha to create a theoretical "best" human run. In the absence of a TAS (and no available TASing tools), this is the fastest time we know this category can be run in.
I'm really happy with how it came out, especially because the final time of 19:42.00 is a full 41 seconds below the current WR, and I know there's more time that can be saved. I have a Vegas project file with the splits set up now, so as I record more practice and get better times I'll insert them into this video and try to keep track of just how low the time can go.
It's also inspired me to start running the category again, since, hey, sub-20 is free, right?