I'm as wary of unicorn hunters as anyone, but you guys actually sound like you're going at it without being overly attached to a particular outcome. That's important.
Thr best advice I can give you is to be completely open to anything. Place absolutely no requirements or expectations on the woman you seek, aside from basic respect and honesty of course.
People with painful experiences in their histories tend to see all couples seeking triads as unicorn hunters, but it's not always the case. There are a select few who just want to expand their relationship to include others. Unicorn hunters don't respect the woman's rights and individualism, but it doesn't sound like that's the case here. My own experience is that seeking specific relationship configurations rarely works out, but it's your life to live and who knows, maybe you'll get lucky.
Best of luck to you both!
I don't need labels to define me. They're sticky and I hate the glue they leave behind.