I thought for sure that with all the save-scumming I've been doing that I'd finish the game before my 20-hour deadline. It seemed reasonable, considering that as of hour 17, I'd gotten all the way to the last dungeon, but boy has this one been a doozy.
However, I think the real culprit here is the healing shoes. After every few steps, they will heal a hit point, meaning that if you're the sort of person who can patiently walk in circles for five minutes, they greatly reduce your need for healing items, and the only thing it costs you is a bunch of tedious grinding.
From here, I'm going to keep going until the end of the game. I'm sure that I'm pretty close to finding the treasure of King Nole. Hopefully, it doesn't take more than a couple of hours.