Thank you for your question!
As per the Post Imperial CRL's:
"To conform more with styles we have seen consistent with the Post Imperial Era, back plates are no longer allowed to have extensions that come up the back over the shoulder like their modern era counterparts. The backplate should, for the most part, feature a straight, or slightly curved top edge.
The only time any sort of back plate extension will be permitted is if the builder is using epaulette armor in the same fashion as Paz Vizsla, Bo Katan or Koska Reeves."
Segmented backplates are okay, but nothing that comes across as "Wrap-around"