I dont know where the spectrebodyhide is i never saw it
Should be in the same folder as SpectreBody is? If anything, you could just duplicate the SpectreBody material and rename it to SpectreBodyHide, and if you are able to use a shader for it that can use transparency, then you can just put the alpha mask in the hide version, since all it's doing is applying transparency to hide the lower body when the Kimono is on