I've been working on distracted recall too but haven't attempted recalling him from chasing prey. I have successfully recalled him in the middle of him playing with other puppies though. I was happy about that.
I agree with the long line idea. I have a light cotton 20' lead that I use for training in the yard. I love that thing.
Linus van Pelt Haus Juris. My Sweet Babboo, born March 17, 2014.
Madeline Ronan Heart (Maddie) Dec 1997 -- November 22, 2013 Rescue GSD, Sable