Re-author with DVDShrink, no compression (ignore warnings about the file being too big), that way I can have just the main movie and strip out all the subtitles and other languages (can't remember if there are any).
Then run DVD-RB (with the AviSynth script) on the re-authored ISO (mount it with Nero ImgDrive or similar, or just save the files to a folder on the hard disk).
This gives as much space as possible for the main movie.
Hope that helps.