..you seem to be overly concerned with data loss with those RAID 1 setups....however, not knowing the REST of your system components AND not knowing the what exact drives you are using makes giving advice almost impossible.
Hardware you should describe :
4. memory - amount and speed
5. drives - exact details on what make, model spinning drives and what SSDs you are using.
Software you should describe :
1. Operating system - if Windows, which version
2. Premiere Pro - which version you are using
3. Codecs - what type of footage are you trying to edit. What codecs are in use from what camera(s)
At a GLANCE, it is known that any current quality SSD under 256GB capacity will NOT perform as well as the models of 256GB and above. Are you SURE that large audio files pertaining to your audio programs, ( audio source files, rendered files, audio preview files,etc.), CANNOT be located somewhere OTHER than the "boot drive" ?? This is important because for best performance it is recommended that ONLY the OS, programs, and Windows page file go on the "boot drive" . Once loaded, the OS and programs become "memory resident" and do not need the faster drive speed that the audio and video source files do.
Bill Gehrke , here on this forum has done extensive testing using PPro and determined that, ( counter intuitively), that the place of the media cache AND cache files makes NO DIFFERENCE in performance !! He places them on his boot drive so they can be easily erased when a project is done...PPro will easily recreate them if ever needed again. However, the placement of video source files, project files, previews, and exports DOES make a big difference. These files all need to be on the FASTEST drive you can provide. With your current system, that might be a RAID 0 of the two 1 TB SSDs. However, if your motherboard is newer and can allow the new Samsung 950Pro PCI SSD to be installed, THAT is where you would would put ALL files OTHER than what is on the "boot drive", because of the massive BIDIRECTIONAL speed of the 950 Pro. Your other existing drives would be used for backing up, archiving, or, as spares. If one of your existing 1 TB SSDs is of sufficient quality, IT can be the "boot drive"