The thing of it is, change the arrangement for one character and you change it for all. Are you willing to alter all of their special poses?
Looking through the Special poses to see which ones would be effected by that change:
DK Cecil (Darkwave): You'd have to lower his sword by like 1 horizontal row, as the sword just barely uses the UL (upper left) 8x8 tile (I'll just refer to as tiles from here on)
Tellah (Recall): The "!" bubble uses the UL tile, but you could just nix that and it would look just fine
Yang (Kick): Part of one his arms uses the UL tile, but you could probably just move his entire pose down 3 pixels and be good
Palom (Boast): One of the cloud-things use the UL Tile. You could nix that one, and turn the other into a straight line with diagonals beside it to show he's yelling
Porom (Cry): The UL Tile is used here for... I guess her tears? Idk. You could nix that and just give her a more emotional looking expression or something lol.
P. Cecil (Cover): One of his hands are in the UL Tile. You could just have him block with a shield since you'd have the BL (bottom left) tile to play around with.
Cid (Scan): His stupid magnifying glass spills over to the UL Tile. You can just move his hand down two pixels and be good
FuSoYa (Regen): stupid ball-shape-thing uses UL. You could just not use that and be good
A lil bit o' extra work to do if you (Fedorajoe) go that path, but a shit ton less than I figured it'd be. I'd say go for it.
(Also wanna point out I think it's dumb Square just didn't use the whole 3x3 area in the arrangement data. Gonna have to rethink a couple characters' poses in my own project now that I know this

)