I have the same sorts of dual-purpose breeds you have. And they have never even attempted to go over the 6-foot game fence around my half-acre. Even the four-foot chain link fence on one side stops them cold. I can't even imagine these gals even challenging that solid fence of yours. But that's just me and my flock. They don't even scoot under through arbividae hedge which I'm sure they could do. But then again, the half-acre they have access to affords virtually everything a hen could want.