I second the Frisco Woods CG. Just make damn good-n-sure you get a spot near, or on the water. The little canal that they have is ok, as long as you aren't too far away from the sound. Check their map. Site B20 or site C15 is about as far down that little canal that will still afford a sound view and awesome sunset. Most folks leave a large amount of space off the rear of their TT, and setup their chairs, small table, etc to watch the gorgeous sunsets when camping along the canal.
Now if you are lucky enough to get a sound front lot, you're in heaven.
I have to agree that camping along the OBX is all about what you are comfortable with. I wouldn't want to be camping in the NP w/o electric in June, July or August, as the heat can be pretty intense, along with stifling humidity.
One things for sure about the OBX, and that's the wind. That's why Kitty Hawk was built, and that's to take advantage of the constant winds. When the winds subside in the hotter months, you're gonna get eaten alive by mo-sqeeeto's. Come prepared.
Boon docking in the fall/spring is ideal, thus the NP's would work. Now, is not the time to be there w/o electricity provided for you, or generated by you.
Enjoy your stay. The beaches are so pristine, and empty. That's the beauty I find the most appealing. You can sit on the beach all day, and only see someone about 2 miles from you. Parking along Rt 12, and scurrying over the dunes to see you are there all by your lonesome, is just plain awesome!
Have fun, be safe, and enjoy your stay. It truly is a remarkable collection of islands jutted off the coast of this great state we call NC!
Forgot to add the "why" I like Frisco Woods. Plenty of hot H2O, excellent views, pretty friendly staff, and most importantly are the rates. If I remember correctly, KOA was in excess of 80 bucks a night. I can find a hotel cheaper than that. I don't have young kids, so a huge pool and activities for them are not needed. Good location for FW too. You don't have to travel far to get supplies/food or eat out.