I don’t have much advise to give here, but a relevant question is: are you planning on running the services (except for torrent client) locally, or on a dedicated server that’s running as the seedbox as well? I think running it all on the seedbox would be the easiest to setup, and, from my understanding, you can pretty much just rent a dedicated server from a provider you trust and follow this guide. Maybe you’ll need to change a few things regarding the routing.