Have you looked into Remote Path mappings? I have not had to employ this myself, but my understanding is this allows you to avoid file duplication when your *arr and torrent client are using different filesystems.
Maybe I'm mis-remembering though...
Technically you can torrent with it, but the free tier does not include port forwarding, so you will not be able to seed very effectively.
Edit: disregard, I was remembering incorrectly.