I would just buy the OEM parts.
https://www.bikebandit.com/oem-parts/2017-kawasaki-z650-rear-fender-s/o/m159441sch1015842
https://www.bikebandit.com/oem-parts/2017-kawasaki-z650-rear-fender-s/o/m159441sch1015842
Free, but you have to come to ThailandHi,
I saw a lot of people changing their rear fender/plate holder and replace it with fender eliminator kit.
I would like to buy the original (and ugly) complete rear fender (without the flashers) because I need it for a mechanical inspection.
Let me know your price.
thanks