I live in central Texas, about 40 miles to the SE of Waco, and if we have enough rain, we usually have plenty of pigs. With deer season over, I've transitioned to pigs/coyotes and I'm having a fine old time. Lately I've just been rifle hunting for pigs, but if I needed more meat I'd set up one or both of my hog traps. The most pigs I ever had in my big trap was (I think) 16. As for the meat, I really hate skinning hogs. Nothing can dull a knife faster than cutting through a mud encrusted hog. Somebody on the forum recently mentioned power washing them first, and I hate myself for never having thought of doing that. As for the meat, on a medium sized to big hog, I'll take the backstraps and hind quarters and use the rest for coyote bait. On a little one, sometimes I'll split it down the middle and we'll cook one half and freeze the other half. As for how much usable meat comes off a hog expressed in % of body weight, I'll leave that to someone else to answer. And if you have hogs in your area, unless we have a famine and everybody drags out their rifles, I really do not think we can exhaust the supply of hogs. After nuclear war, there will be cockroaches and hogs left.
And yes, we can hunt them year round (you do need a hunting license), though if I shoot one in hot weather I usually don't mess with keeping the meat.
Leave Missouri and come on down here to Texas. Like many folks are fond of saying, "I wasn't born in Texas, but I got here as soon as I could". I promise that if you move to Texas, you will (almost immediately) be taller and better looking...and smarter. I think one of the guys on the forum just moved to Lubbock. Maybe he'll back me up on the taller and better looking issue.
And now..right now... I'm going to grab the 260 (or the 220) and go pig/coyote hunting. Wish me luck.