It will cost you $60 to resign your saves. Yeah, it's insane.
Just wait for a free save editor or save resigner. I'm sure it's coming soon, I seen a few people working on the Decrypting/Encrypting tools for Save Games.
Not possible yet, @godreborn mentioned that he may have seen or heard about fake save data option on debug settings, but it might not work or might have been on a lower fw.
I dont have my PS4 set up to check right now, but I'm sure its not usable right now on 4.55.