We have ours built from stock panels also. We've built a couple different types and finally, after trial & error, we kept the same design but made the traps stronger. One design is strong enough to take a hard lick and knock the hog nearly unconious. They other, similar to what you have built, is strong enough to hold them, but it flexes. I don't have any pics of the really sturdy trap, but here's a couple of the one similar to yours.(I think)

A view from above. Also we lined the inside with a smaller mesh wire and cyclone fencing to keep those little (crockpot size) piggies inside. Yes, they can fit thru the holes in the panels. We also , used the surrounding trees for support.


Here's a pic of the same trap with 5 60-75 pounders in it. 3 sows & 2 boars.



What you think is strong enough,...isn't! We watched a sow about 150lbs walk right through our other stock panel trap like it wasn't there. She broke several welds on it. Now we have it triple-layered and haven't had a problem since...............YET!