We have been picking times when she doesn't appear distracted by anything in the yard (aka not in hunting mode) and when the chances of deer/skunks/etc. appearing in our yard are lower (so mid day and not morning and evening). We stay near by and have her drag a leash so we can step on it if hunting mode kicks in. It has been going well and she has been able to be off leash for 5 minutes or so with no incidents.
This makes us happy!