Jack,
I use traps with tops. Your big hogs will jump 6 foot walls. The little smart shoats will jump onto the back of another hog and then jump 6 foot walls. Once you see it, you believe it. Until then, it seems like something out of a cartoon and unbelieveable.
I use guilotine gates. My trip latch is a 32 inch piece of one inch tube steel cut in half. I weld a hinge on one side and a washer to one of the 16 inch pieces on the other side, for an eye. A cord goes through the washer (eye) to a pulley that takes the cord across the bottom of the trap. When a hog hits the trip cord, the tube steel folds in on the hinge away from the entry and toward the center of the trap.
Set the trip cord about 16 inches up. Pigs will enter, then a shoat or hog will enter and trip the string, catching them all.
The pen grid in the pictures is the right grid. Cow panels will not work. That design may catch a lot of hogs, but it will not work for me. What you have to bear in mind that many are simply satisfied with catching themselves some hogs. I am satisfied when I catch ALL of the hogs. If there are 150 hogs out there and I only catch 140, the remaining 10 will multiply exponentially. A hunter would be tickled with catching 50 and that trap design would be great for him.
Any hog that escapes a trap will become trap smart and difficult to catch. I do not take chances. That hog will continue to wreak havoc on my property and my investments. I am already marginal in making profits. I don't want to give meager profits to hogs, or anything else for that matter.