Quick update:
The two main sidequests are all done. There's 3 more "mini" quests as well. Every town/dungeon can be revisited after you get the airship, for treasure collection purposes.
It's basically done, but some of the more recent enemy additions are harder/require more strategy than the older ones, so I'm going to tweak them around during my next playthrough in addition to the last couple things on my list.