I figured it out, finally. And we may have a problem; DK Cecil, Cain, Yang, Cid, Edge, and Fusuya all use the same field palette, if my limited dicking around is any judge. Paladin Cecil has his own, of course, and both versions of Lydia share one with Palom and Porom, and Gilbert, Rosa, and Tella use one. Golbez has his own, of course, but he never appears as a PC so it doesn't matter.
If you don't want to tweak the colours on the palettes, you could conceivably squish them all onto one 4bpp palette. (There are a total of fifteen colours across the four PC field sprite palettes, with the Rosa/Gilbert/Tella palette being the only one where half of it is unique; the other three share orange and a shade of blue, and all four use transparent, black, and two skin tones in the same slots.)