To be honest, Seasons at Prince Creek is the only one I can think of.
They are probably more like 3 or 4 miles to the beach, but they are around the square feet you are looking for. They are well under your price range - current listings are between low 200's and upper 300's.
With the exception of NOT being an adult community, there are many communities that fit your other criteria in Pawley's Island. Just an example: Heritage Plantation is a gated community on a golf course (Heritage Club), about 2 miles to the beach, homes over 2000 sq ft, under 500K, with a pool and tennis courts. And there are others