When I took over a lease several years ago, all of the feeder pens consisted of cattle panels that were cut in half, lengthwise, down the middle so that there was a "spike" side protruding along the whole length. When I would move them around I tried putting the spike side down, sticking into the ground, to help hold them in place but the bigger pigs would crawl over. I tried reversing them so the spikes are on top, sticking up, and no pigs have crawled over since. Sometimes the small babies will walk thru the larger openings but have had no adult pigs in the pens.

You should try hog panels, they work really well.