Alldunn, you shouldn't be riding on dunes anyway. They are vital to the eco-system and have little animals in them ect...
But the roads in Carova, NC like Ken said are/were fun, but I haven't been there since my parents sold the beach house.
Dunes kinda suck anyway, you should go to Paragon next time or Uwharrie (Baden Lake) NE of Ablemarle has some trails or head to Tellico near Murphy.