My boy has since passed on, but he would never consider leaving us. So we just let him off the leash on the trails. Whenever we heard people ahead of us we'd call him back and put him back on the leash until they were out of earshot again. It never caused any problems in the 12 years he was with us. Such a precious, beautiful boy.
I wish he was good enough for that but he believes he's a hunting dog and if he smells deer scent he's gone... He event managed to dig out a portridge once! He picked up the scent, stopped listening to us and 30 seconds later bam, bird came out of hiding 10m from us and our dog came back as if nothing happened.