You'll have a blast! I'm assuming that you're using catch dogs, so you'll have to be careful with a HUGE knife. I've hunted with a 9" blade, and it's fine on a bigger hog, but on the little ones (say 75-100 lbs) you can easily stick through the hog and endanger the dog on the other side...
A 7"-8" blade would be plenty big enough for anything you may encounter, but not so big that it would be dangerous for the dogs.
The Guard is very important, it often takes more than one stab, and things get wet and bloody quick. Most guys get hurt by allowing there hand to slip onto the blade, not from the hogs tusks. So do something with a substantial guard.
Then, it just need to have enough point to penetrate, and be stout enough to encounter bone and such. Any of the steals in 3/16 or even 1/4 would be awesome.
Finally, spend some time thinking about sheath retention --- you'll likely be RUNNING through the woods / marsh, it's very easy to lose a good knife that way.
I'm envious that yo get to design your own blade! Good luck.