At the moment a lazy solution I use for this is to configure the recycle bin. It somewhat fills the requirements (keeping the files), but doesn’t leave them in the series folder.
Ofcourse everything is dumped into a single directory, but the files are already renamed so it’s easy to find what you want and do a manual import (or move them into the correct series folder again, delete the other files, and trigger a rescan).
Yeah, I have a discarded files folder instead of sending it to recycling bin but I’d like to just disable it completely. Since i’ve started using Sonarr over Sickbeard, I’ve found my self searching for files from the Sonarr more often than using the actual indexers websites. (its quite mobile friendly!)
But especially at the start of a season I’ll download quite a few releases of at least the first few episodes to see whos doing the best rips and i’d like if they could all just stay in there one place)