If you are an Adventure Cycling member, post an ad in their companions wanted section. It can be tough to find compatible partners, but they are great to have if you do.

FWIW: There can be advantages to mixed gender groups. I think that we had the ideal mix for our XC tour last Summer with one 56 Y.O. man and two 21-22 Y.O. women. We were never hassled and were treated incredibly well by all of the locals. Everyone assumed we were a father and two daughters (one was my daughter the other not). As a result I think we were more approachable in a good way, but not as subject to negative attention as most groups would be.

I felt like that was an ideal mix and we hope to all tour together more. If I were in the market for touring partners it would be great to duplicate that mix. It would be hard to run that ad without being assumed a dirty old man though.