Why don't you guys just plan for another state-wide jam, but extend an invitation to the national community. Talk to various community leaders around the country and encourage them to come with their local communities. The big national jams are big because of the media they generate and also because they tend to be held in big cities/tourist locations. Beast Coast in DC, COPK, New York, etc.
You guys have a huge regional community. Even if you advertise for a National jam, NCPK will still show up regardless of if others don't. Having said that, I would love to go to a jam in North Carolina, but unfortunately I don't think I'll be living in the U.S. in 2011. Good luck though!