Can you camp next to the sand dunes, or is there access to get to sand dunes with your atvs from the camping spots.

There's camping on the beach at sunshine (?) Campground, but not right at the sand dunes. And yes there are trails for your ATV's and motorcycles that will take you to the sand dunes by the reservoir. Be careful, there are some more sand dunes on private property.

Semino boat club road has roads off it that leads to sand where you can camp.

Honestly I don't know... but I'm sure there's a way...