First of all, thanks for this great script. It is pretty close to my prior handmade Seedbox setup and it was so easy to install my newest dedibox.
What I would like to suggest ist the integration of rar2fs.
This is a FUSE file system for reading rar archives. I really got used to it, since in my opinion it is much more convenient to unrar “on the fly” instead of unraring every single download.
I would be glad to see it in one of the next releases 
https://github.com/hasse69/rar2fs
Feedback is welcome