I visited Ross Back Sands in June. It's a lovely beachwith terrific views of the Holy Isle and Bamburgh castle. There were a few couples relaxing in the dunes but it wasn't very busy. Having said that it was a weekday, so maybe it's busier at weekends.The beach can be a bit breezy but the dunes are sheltered.
It's a fair walk from the car park to the beach through the hamlet and farmland. I think I took the wrong path as I had to wade through a wet marsh. It would seem that you should take the path to the north (I went straight ahead). On the way back I was able to enjoy a brisk naked walk around the southern part of the farm/grazing land, as it is flat after the dunes it was easy to see anyone in the distance and whether they were coming in my direction. I only had to put my shorts on as I was coming towards the gate. I think I might have been a bit too adventurous though, and don't know if it's etiquette to bare all outwith the actual beach/dunes as I understand it's a naturist tolerant as opposed to an official beach. I don't think I would do the same another time.
Having said that I've been waiting for the weather to give me the opportunity. I was lucky the time I went as I had been down that way with my job. Any other time I would need a sunny weekend. And that just ain't happening in northerly parts.