Jeff,
if you can find an empty fenced in area,
(i use empty fenced in school yards, football fields, the old ancient cemeteries, fields, anywhere there is a fence)
These areas are great for recall. Put dog in a "stay"
and walk away, (just like, 5 or 10 feet at first) and call dog.
or wait til dog is busy sniffing, sneak away, and when dog is done sniffing, call him over. (dogs sniffing are hard to call to you, so set your dog up for success at first)
The other thing i'm doing, teaching sort of a default "stay within a few feet of me"
I am doing this:
If my dog walks too far away from me, i make kissy noise, and reward him for returning back to me, alternating between praise and treats.
While we are walking through these fields,
i make sharp turns,
if my dog doesn't turn along with me, (i'm talking generally, not in a heel)
i make kissy noise, my dog then begins walking in same direction i am walking.
Now, more and more, my dog is now "getting it" and beginning to turn and walk in same direction i am (again, this is NOT his heelwork, this is just casual walking in same direction)
it's fun, imo.
then, i also "release him" and say "go play" and my dog is free to go run around, til i call him back to me. At first, i threw toys for him to chase, or treats onto the schools's running track, and praise him for being far away from me,
and then, after a while, i call him back.
hope that is not confusing, what i just said, but, my dog mostly "gets it" now,
somehow, my dog HAS sorted out, "i should stay within a few feet of mom unless she says go play"
and he does.