in theory, a repack is possible. I've seen it done here for other game, but there's no guaranty either since SV's version of Yuris engine has the reputation to be difficult to work with. Given that, i won't take a shot at it; i don't have the competence anyway.
That said, if you are really desperate for every ounce of free space, i know how to easily shave 500 mb of the game. It involves deleting the files containing the opening, and the various ending scrolls. I didn't test this trick on the translated version, but i can check if it works provided that someeone is interested. I played for about one year with that "shaved" japanese version, and never came across any problems, so it's worth a shot for those who need that little bit of free space.