Hi!
Have a look at this Ultimate Guide for Naturism in Croatia. It has an overview of all naturist campings and the best nude beaches in every area of Croatia.
Also check out the Extended Version which has even more info, lots of tips and a complete review of Camping Baldarin on Cres island
See the guide here: https://www.nakedwanderings.com/naturist-guides/#Naturism_in_Croatia_The_Ultimate_Guide_2019
If you're in Dubrovnik you can get the little boat across from the old town to Lokrum. There is a naturist portion on the far side of the island. That was my first exposure to public nudity back on a holiday there (still Yugoslavia then) back in 1982.
I'm Pete from Kent, hope that,s useful. The islands are good for nudity. Had a nice time on Brac a few years ago and there are good nudist islets off Hvar main harbour