SMalbany,
The security guard suggested that we park in a gravel lot adjacent to the checkpoint. (In other words, she didn't let our car past the barrier.) No problem -- it was a short walk from there to the beach, and the security guard told us that we were welcome to walk to the beach. While you're parking your car, you can visit the crowd of iguanas gathered there. (They are used to being fed, so they beg.)

Even though there is sargassum on the beach, you can certainly find a clean place to spread your beach towel or set up a folding chair if you want to. That said, Dawn Beach has all the usual problems it has always had -- lots of waves, and murky water that makes the spot unsuited to snorkeling.