Ultimately, this is the overall approach I took. But for any code I write which makes use of RegEx, I strive even harder than usual to make it readable. RegEx doesn't have to be as hard to read as people make it out to be.

For anyone curious what a more readable RegEx solution for this might look like:
https://www.codewars.com/kata/reviews/520446778469526ec0000004/groups/5ed642bd8792a0000147e74c

clever indeed, except it works only for m <= 30

Yep, missed that for legibility. Good one. ;)

this is the kind of answer that keeps me up at night.

Ha yes it is :)

Dang that is nice.

well it certainly is compact.