

As the other comment says, use hardlinks and then you can have several copies of the file across the same partition all reference the same file, using just the storage space needed for one copy of the file. Still RAR files will need to be extracted first, so those would require just about twice the file size, but hopefully people stop using rar, so that’s not a concern.
There are some niche private trackers which have an active community that handle quality and requests. Also they don’t let just anyone create a torrent, so you can have assurances that the files have been vetted to some extent and you’re not going to download something unexpected.