OMG man Frisco campsite is like seriously the best thing ever, man that place it super cool, Im not joking. It's like $20 a nite but you might be able to sneak in there for one night. Some friends and I did once, we just came in late during the night, right off the Hatteras ferry, and there was no guard. I guess you're on the "honor system" but we were real low on cash by the end of our trip, so we just set up a tent real quick and then left at about 8am. The man at the gate, stopped us, and we told him we just came in real early to surf and we were just leaving. He wasn't happy. but he let us go! haha I know that was wrong but we only did that once... but if you can, Go to site B-12 - it's about the coolest site. It's down off the road a bit, like down into some trees and its real secluded.. super chill and awesome walk to the beach...out across these long boardwalks crossing marshy area to the main dune. Check it out!
Other places, Oregon Inlet is a good halfway point. It's pretty open but there's some cool sites there, nice walk to the beach-through the dunes-but don't get hammered and try to go to the beach. I did that on my solo trip and I got lost and thought I was on a martian landscape haha.
If you get to Ocracoke, skip the National camp site. Go into town, to British Cemetery Rd. and go to Teeter's Campground. That guy is super cool as hell, and he will let you stay (if your party is small) for about $15 a night. PLUS there's hot showers there, and power. Then go get lost in town for a while. Hope that will help you out. Let me know if you wanna know more. I hit a bunch of places down there including hostels and backyards, and squatted under a house or two for a night or so.
In November, a few of us went to the Sands of Time campground in Avon.
It's a small place, and the a potential problem is that there aren't many tent sites. We didn't have a problem getting one though. Maybe a good backup place to go for a few days if swell/wind is bad somewhere else.
The main positive is the accessibility to the beach. If you are looking for off-road access, it's available only about a mile from the campground. You can surf near the pier to the south or just keep driving forever north looking for a spot.
You should be able to search and find it on google.