I haven't been successful with making my own perforations yet. My 500 is a beater so I cut off the finger. Now I can wind it 2 times per shot for sure single shots or if I want to chance it, 1.5 windings to get more shots per roll. This works perfectly for the roll of 100' Portra and the Rollei Retro 400S (both unperforated) so I have both C41 and B&W to bulk load. I develop both in my basement.
I'm also buying old Verichrome Pan which works great too and then I have more backing paper to use which seems like the most vulnerable part, the cartridge and spool are tough but the backing paper starts to get crinkled after a while and I suspect it is only a matter of time until it rips. I still have several backups to use, then I'll have to buy more expired film for the paper if nothing else!
Your yardstick idea sounds interesting. I'm doing my loading in a changing bag so far which is probably why the punching hasn't worked out, just too cramped.