IMO, looking specifically for compatible activity partners is about as painful as dating.

I think that classes are a great way to meet people whether we're talking about activity partners, romantic interests, or whatever. A class creates an low-pressure environment where you work with your classmates and get to know them. If you find that you enjoy working with some of the people in your class you can continue to meet up with them afterwards. If you find that you don't like them, you don't have to see them ever again.

Maybe you could look around for clinics or community college classes for outdoor skills like wilderness first aid, etc. You'll have a good chance of meeting someone likeminded about hiking and then you can branch out from there. Worst case scenario - you'll walk away with more knowledge and experience.