I'm using electronet around a minimalist range shelter. It's a large fenced area, and I move the shelter within it every day to spread the manure buildup. The feed trough and waterers are under the canopy. I figure it will be trashed in about two weeks, and I'll shift the electronet.
I'm using existing ground rods, and just adding more cable out to the fence. Pounding ground rods is a drag, it's much easier to run more supply line out to the fence.
Last night we were awakened by screaming raccoons, but the chooks were still sleeping when I went out. Don't know if the screaming had anything to do with the electronet. The dogs escorted them away from the barnyard.
My only worry is owls, as the chickens don't grok going into the shelter at night, and sort of spill out.
Now, if you want a physically strong tractor-type pen, I've made one out of salvaged grid panels -- the heavy wire grids they use to make store displays and mall kiosks. I'm not really using it because I have too many birds right now -- it's good for maybe 20 birds, and I'm ranging 117 five-week-olds.
I just don't trust a physically strong movable pen to hold off bears, large dogs, coyotes, or raccoons. The latter will reach through to get birds.
I'll post pix of the grid-panel tractor later.