Sorry Andy, I cant help, I don't use many sites and went to Spain once in the motorhome and had such a scary time, we went back to France after just the one night!
Not been back since but it was at least 25 years ago.
However many on here love Spain, so hopefully someone will come forward.
I know there is a euro campsite in la manga, all singing and dancing with swimming pool, short walk to the beach.
There is also an 'aire'/overnight parking listed here on the CM Spain listings, but as I said, I haven't been myself!
Rolling on and enjoying life on the road