Okay, a month and a half later and I finally got around to doing this, and....
SUCCESS!
Looks like task29 was what I needed. Here's my upgrade process:
- Started with stock SPL, MR1
- Upgrade to Hard SPL
- Ran task29
- Flashed MightyROM FF
- Ran clearstorage
Several days without a hiccup.
Thanks again everyone!