I've camped out on Bellows beach (military ID req). I've also camped out near Ka'ena State Park, but nothing that any of the forum users would call "overlanding". I mean I've gone out to Kahuku and went dirt biking and decided to camp there instead of do the drive back, or go out to Hale'iwa the night before to get some morning waves, but thats about it. Honestly you could do a bit of overlanding on the Big Island, but even then you are no more than an hour from civilization. You can get some serious offroading at Peacock Flats or at Sand Island, but that is about it unless you make your way to Maui.