Ooops, didn't read the op well enough about the "on the trail" part
In my younger days* ...
Successfully via knowing a woman from an urban setting previous to a trip. In my case, about 10 years ago with a woman in the same backpacking club with me when I helped to plan and lead trips. We had gone on a couple trips, started to know each other outside of backpacking (she introduced me to contra), .. but she was the only one to sign up for an AZ trip with me. Romance kind of blossomed after that for several months, until I had to leave the US for a 1-yr job assignment. She decided a long distance relationship wasn't for her and we split up before I departed.
Add: The closest I've came to "on the trail" was in a fairly populated backcountry campsite after returning to the states. A contingent from a large hiking group (big enough to charter a bus and break into smaller interest/ability groups) camped near me and, being friendly but also very single, I struck up 2 separate, very long conversations with a lady meandering towards my tent; talked about the views, the trails, my lightweight gear, etc ... before "Dear Leader" of their group butted in, corralling her back to the group; now passing the group on the way down, he snickered about my trail runners and loudly proclaimed how trad boots were the only way to go - should have given the middle finger salute. He had some bad karma later that day anyways, as the TH road partially washed out and their bus couldn't make it, ... they hiked down to it those same trad boots a couple steep miles, delaying their return to the workweek. So a popular campsite is a good place to talk to a people ...but with women, there is increased male buffoonery in most group settings.
p.s some hikers may be into solitude experience and that needs to be respected too
p.p.s. *now I just hit square dancing night at the Elk's Lodge for the blue haired ladies with big life insurance policies .. and unfortunately, not Katy Perry blue.
ed: add, p.p.s