Memorial Day is a good time for that itinerary. Been to each of those places many times; they're about 1.6 RV hours away from us in the mountains
FFA has a one night only policy that is strictly enforced by the Park Service. It does not offer hospitality for extended stays at the OBX. Landing and returning does not reset the meter, either. It's one night per month. The Wright Memorial and museum are must-do local attractions. Beaches are not convenient by foot; you'll want a cab or bikes.
Manteo (MQI) is where you would want to tie down for an extended stay at KDH or Nags Head. Very nice airport and FBO, offers mogas and self-fueling. I recall that only one of its original three runways is open anymore. Lots of banner towing and GA operations out of there. Plenty of sea gulls, too. Be vigilant and stay on the radio. Bring gust locks; the wind never stops.
Okracoke is awesome. The runway is a short walk from the beach, which is never crowded. Bring bug repellent or the mosquitos will eat you alive in the privy when you relieve the P-factor after landing. Howard's Pub is one of the best eateries on the island, and the only one within comfortable walking distance of the airstrip. They offer golf cart pickup for patrons who phone or call them on Unicom, which they typically monitor. I've rented bikes from the island realty companies ahead of time and had them lock them to the fence for use when I arrive. Easy. A bike is all you need for exploring the populated end of the island. No fuel available and no services either. There is Verizon cell coverage.
Let us know how your trip goes. My new bride loves the Carolina beaches and we are looking forward to many day and one-night trips there this summer in the 6A.
-Bill