I just found an ugly bug: checkpoints aren’t compatible with smPlugin. 
Checkpoints each have their own “save slot,” but smPlugin uses the legacy “password” system, which includes the current playthrough’s save slot, but not the checkpoint save slots.
That means that even if Dashingdon and/or Moody Ink were to include my latest code, if you *save_checkpoint at the start of chapter 3, then save in the middle of chapter 3 with smPlugin, then restart the game, and then restore back to the middle of chapter 3, when you *restore_checkpoint at the end of chapter 3, your game will crash.
I’m… going to have to think about how to fix this.
I think I can gradually begin that process.
For my first guess, I think the main thing to do is just to make it super, super easy for people to use a tool like CSIDE (at first, probably literally CSIDE) to generate a single-file HTML file for their game, and for that HTML file to include a unique storeName (perhaps based on the IFID?).
That way, people can just upload HTML files to Itch.io or something…?