organizing ebooks and fanfic

I currently use Calibre to organize my ebooks, and I wonder if it would work out to use it to backup and keep track of the fanfic I downloaded on my tablet as well.

I do not want both mixed up, because the fanfic would totally drown out the books by an order of magnitude, and also the tags I want to use for both are very different. I've seen an option in Calibre to create virtual "libraries", but I wonder whether that is really good for keeping things separate. Has anyone experience with using Calibre for both? Or a better system?

I'm a bit wary to import hundreds of stories into my Calibre Library only to find out it would be a mess I'd have to clean up manually...