Would it be possible to combine discs one and four for each film, at least to an extent? I can’t imagine the films alone weigh that much on a BD. Maybe a BD-50 version can do it?
That would be especially tricky for ANH as, if I’m not mistaken, no one has gotten seamless branching working. The 77 and 81 crawls are going to need to be separate encodes of the film, likely requiring a BD50 for that reason alone.