I actually did two 30 rides from Corolla last summer. There are adequate shoulders to ride on in the Corolla/Duck area. As has been said, leave early. Almost everyone sleeps in on vacation, but by 8am the Duck bike paths and lanes are crammed with runners and beach cruisers. By 10am the traffic approaches scary. There are always a ton of roadies in the area. Two strangers were nice enough to let me paceline with them up by the Corolla lighthouse last year. Early in the morning it is a great place to ride. Get on the road by 6am or earlier and you can crank out a few hours and still be back in time for breakfast with the family.