most of the outer banks are open to ORV. Outer-Banks This will take you to a website that lists all of the places on the Outer Banks that you can drive. You can also drive on Carolina Beach all the time. Hope this helps
I hear that Emeral Isle is open to beach driving but you have to get a permit at Emeral Isle Town Hall. Also Atlantic Beach between the Sheraton and Tf Macon are supposed to be open but I don't know the details.
I believe that Emerald Island and Atlantic Beach are just between Labor Day and Memorial Day. I'm taking the Bronco up there to check soon, so I can post if I get a permit or not. I'd gotten them in the past (cost like $5), but I haven't gotten one in several years.