I always felt I had a better chance of getting permission when I asked in person. I had a good bit of family in that area years ago (most have passed now) and most of the farmers knew each other so it was easy. I haven't hunted down that way in probably 15 years, so I don't have any direction to point you in.
I would start with a specific county and look up that county tax gis map and get a landowner and go ask in person.