I would forget partitions they just add overhead.
It would be better to have a second SSD for Project files and use the first just for OS/Applications.
What about temps (cache)?
I've heard that cache need speed the most, maybe it's a good idea to make ramdisk and have over 6k MB/s (read)
I have tested on my systems and once the Premiere "Media Cache" and "Media Cache Files" are on any decent SATA III SSD, even the default OS/Applications SSD there does not seem to be any measurable performance improvement with any media that I have tried. As an example my PPBM h.264 timeline test has 7 different media types.
Maybe some other media types might show some performance differences but I have tested many different types. I have seen bad results where lousy LAN connections were used for media and Media Cache.