Wow, did it take me a long time to see this comment.
That seems like an interesting way to complete the 18th layer, and I think I've actually seen a YouTube video that showcased the approach. I would have included this in the description if it hadn't been so long already, lol.
Also, thanks for looking at the guide, man! It was fun to write (if you couldn't tell, haha). I'm glad people find it helpful!