A hog trap is simple and effective. Build pen out of heavy wire livestock panels and t-posts. On one end put two panels together in a V shape pointing into the pen. Bait the trap with corn. Leave the point of the V open for the first few days. Gradually bring the panels closer together until hogs get used to forcing their way in and out. Then bring the panels together to make a V. It's kind of like a huge fish trap. My father and his buddy have killed truck loads of hogs this way. Hogs varied from pigletts to a 350 boar with big tusks.
If the hogs start to figure out how to get out tie the panels in the V with parachute cord leaving enough slack to come in but not enough to get out.
Be careful when dipatching the large boars. All you need is a .22LR but if you miss their brain they will try to run through the panels at you.