Your best bet is think like a deer hunter. Scout the area out. If you can find where the feral/wild pigs are feeding, set up a trail/game camera to try to get an idea of what time of day they are coming to that area. Then, set up a tree stand. When the piggies come by, you usually get one shot before they scatter. If there's no limit, try to line up two pigs so you can get a through-and-through on the first, with an impact on the second, if the rounds you're using are powerful enough.
Yes, they are smart, and will attack dogs and hunters. I'm a member of several fishing boards, and some of those also have hunting boards with them. One of those, a local one here in OK, had a picture of a 100 lb + feral hog that tore up two dogs pretty badly (I don't think the dogs lived). The hunter was faced with a situation where he couldn't use his firearm. He jumped on the pig and killed it with a knife. Gutsy or stupid, your call.
Here in OK, you just have to be legal for whatever is in season in your area to go feral hog hunting. If I'm not mistaken (I'm not really a hunter, just like to go fishing), coyotes are in season pretty much year-round.
I do know that a Wildlife Management Area about 10 miles from me has a pretty decent population of feral hogs, enough that the piggies are invading into the neighboring farmers fields and ripping up crops. There is also supposedly a small population of Cougars preying on the feral hogs.
My parents saw a cougar behind their house last year. Just recently, they had four Bobcats in their back yard (I've seen the pics). Probably a mother and three nearly-grown cubs.