Version 2 of the carrier will look a little different. I had the carrier attached to the back of the tractor and went up on a big pile of wood chips. backing down the pile, the carrier caught on the ground, and I bent it up pretty well.
1) the expanded metal works great to exclude pigs, but tends to split if it's stressed at all. You can see in the photo above that there's a bit split in it. That's a bit of a problem. So I'm only going to use expanded metal for the first 12" off the bottom -- basically the piglet zone.
2) the sides weren't tall enough. I had a couple of pigs jump out of the carrier, and that was a bit of a problem. They didn't do it when the tractor was moving, but if I left them for any amount of time they'd think about it. So I'm going to extend the cage vertically to about 4' tall on all sides .
3) I'm going to make the gate a bit bigger. The opening was narrow, but it was hard to get big sows in and out of it.
4) the barrel bolt on the gate was just too much of a pain in the ass to use. I'm going for a simpler throw bolt arrangement that can be latched in a hurry.