Speaking as a unicorn, the best place to find us is on Tinder, OKCupid and poly groups on FetLife. You could post a personal ad on here as well - if you found someone here, at least you'd know they understand kink and you could work that into your scene if you want.
I live in a kink & poly friendly city of about 2.5M people. I can keep my search parameters to less than 25 miles. Sounds like you'll need to open that up significantly and you may want to make your location the closest large city (assuming you're willing to meet there).
When you build your profile, tailor it to the app and the users on it. For Tinder, keep it concise and specific. Be clear about what you're looking for, that you're playing as a couple only, and post pictures of both of you even if they don't include your faces. Understand that at least 50% of the Tinder profiles are fake/scams. Vet carefully, make sure they're real, meet them somewhere public the first time and go from there.
For OKCupid, you have room to be more detailed with your profile. And you'll expected to do so, otherwise, people will think you're fake. Don't write a book and include lots of pictures. Again, be specific about what you want. You'll find most of the people on this app are poly couples and quite a few practice BDSM. The majority of the profiles seem to be real, it's just a much smaller user base, so don't expect the volume you see on Tinder.
I use FetLife as more of an event search tool. We're still getting out of the pandemic, so events have been slow coming but the clubs are open and I'm seeing more munches getting scheduled. Munches would probably be the ideal way to find what you're looking for. Who wouldn't want to meet a variety of people at one time, face to face and know immediately if you click rather than going through the rather lengthy process of finding someone online? So, definitely look for these and take advantage of them if you can.
The biggest piece of advice I can give you is to understand it's going to take some time find the right person, so be patient. Set realistic expectations. And of course, condoms.
Good luck!