Keeping them inside the netting.

So I lost all of my chickens to foxes this summer, because they like going over the net to explore the further reaches of the farm, but can't seem to figure out that they can just as easily go back over the net the other way. Inside the net was plenty of water, grain, scraps, green grass and everything else a chicken could want.

I want to keep using netting so that I can move them on a regular basis to follow the cows and goats as I rotate them through the field, but how do I keep them from going over the netting? I thought (too late) of stretching a single strand of aluminum or maxi-shock wire at the top of the fence from edge-to-edge about 18 inches in from each side. Alternately, I could bang in t-posts at the four corners of the netting each time and run a strand another foot or two above the netting.

Has anyone tried either of these ideas, or had any luck keeping chickens inside electro-net?

And what about clipping wing feathers?

Thanks.