2WD in NC Sand
2WD is not a safe bet in the NC sand, unless you have WIDE tires for the weight of your vehicle. You might get away with it a little bit, but not for long, and not worth the risk. My Samurai on aired-down 30x9.50 ATs could run in 2WD at Hatteras and Ocracoke most of the time, but if I stopped in the wrong spot (soft sand), I'd have to get out and lock the hubs.
I'm up at a rental house in Carova this week, and my 4WD 1990 Suburban on aired-down 33x12.50s will go wherever with no problem. But I've stopped in sand at the entrance to the Oregon Inlet access before, where it was really soft from people driving on it, and I had to stand on it to get out. So you never know what's going to happen - even with 4WD and a locker in the rear.
With a 2WD, if you keep moving, you might be OK, but when you inevitably have to stop (someone in your way, or you want to park on the beach), that's when you'll be in trouble.
Edit - you could get away with 2WD in something like a Baja Bug or dune buggy that is light in the front, engine in the rear, with huge rear tires, but I don't think that's what we're talking about here.