Zozma: yes, that is exactly what I want to do. It's a two-stage process.
1.) Break off the Edge sprite from the rest of the group.
2.) Assign to that sprite one of the vehicle color palettes not normally used by any playable characters.
If you can tell me how to do even one of the two, that would be sweet. I have some ideas but I haven't explored it yet as I've been too, well, really fascinated actually tinkering with other things in the rom. This is quite fun once you get the concept.
Edited to add: I'll just tell you, the main point of my hack is that I replaced Edge with Golbez. Edge becomes an NPC, but he's still important. He avenges his parents, he helps to work on the airships underground, he participates in the battle against the giant, and he takes Golbez's spot alongside FuSoYa in the finale. But when Golbez joins your party after the sequence with the giant, I want his overworld sprite to display properly in all environments, and I want the palette to be EXACTLY right. So while I was able to switch the sprites easily, I haven't found a way to change just this one sprite's palette without screwing up Dark Knight Cecil, Kain, Yang, Cid, and FoSoYa along with it.
EDITED TO ADD #2: Never mind! I was playing with this tonight and I figured it out. For those who aren't familiar, here's how to do it.
Location ABF4A is the place for Dark Knight Cecil's palette and the value is 00. The other actors proceed in the usual order.
00 Dark Knight Cecil
00 Kain
01 Younger Rydia
02 Tellah
02 Edward
02 Rosa
00 Yang
01 Palom
01 Porom
03 Paladin Cecil
00 Cid
01 Older Rydia
00 Edge
00 FuSoYa
The next few palettes are:
04 Yellow Chocobo, Hovercraft, Airship Enterprise
05 Black Chocobo
06 Airship Falcon
07 Big Whale
I would imagine the actors after FuSoYa are the vehicles and maybe Golbez and Anna, and that the townspeople palettes are 08, 09, and 10. Haven't experimented with that yet, though.