Hmmmm, you need the pro's advice on gap size of each type of fish to be certain.
The simple answer would be go as big as you can, until they might be the size that could eat your stocker YP, HBG. I would think that a 10" SMB "might" eat 1/3 its size, so that leaves your current spawn as nice snacks, but your stockers safe. I don't think you could go smaller than this to be efficient.