I have found them in New Hanover, Iredell, Catawba, and Rockingham Counties in NC, as well as one near Danville, VA. The New Hanover was out crawling in the morning in an open sandy area. The others were all found (either on the crawl or under tin) near plowed fields, soil was more of a red clay...typical of the piedmont...but the fact that the fields were plowed may have played a role. Also seems that I've seen them in March/April more...a little earlier than most other snakes.
Hogs seem very random to me...5 live snakes in 20 years of hunting snakes in NC. I would say that you'll have more luck heading one or two counties SE of Wake Co...sandier soil there.
Good luck. If you figure them out, please let me know.
Thanks,
Michael