Btw I was tinkering with the game and I found out that it already has built in a feature that can speed the sprite progress immensely.
You can display sprites of other stuff that already have sprites and then apply a color to match how it looks on the puppet.
It's not a perfect solution but it could be applied to underwear.
EDIT: In fact, someone made a mod with a bunch of maid outfits and they used the maid dress sprite for 3 or 4 of them, so it could be used for some outfits as well.