Other than through open-minded hookups, the other way I've been most successful is through BDSM groups at camping/outdoor events.
These groups are full of people who have a playful kinky mindset, and I've always found people to either mess me up (even if they aren't into it, they see you are into it, and many kinky people are happy to help you with your kink if it's clear you enjoy it), or jump right in, if I had everything set up for cleanup.
Check with the people running the event to make sure it's OK, set up to protect the environment, clean up after yourself, and before you know it, you'll be teaching classes on messy play! (at least that's what happened to me).