I thought about trapping them and selling them, but if people eat the trapped hogs, then they have to have documentation proving that they have had all their shots and whatever else the FDA requires of livestock. While rare, I have read a few stories of people being fined for doing this. In one case, the guy who was being fined wasn't even selling them, he was giving them away!!!
Just shooting them seems to be the best way to keep them away for the longest, but they always come back and the day it happens, the place is a war zone.
As mentioned already, there are practically no rules on killing them. Day or night, no limit, open all year, and now you don't even need a Texas Hunting License if you are on private land.