The water temperature at SSB will be just fine! It is a little cooler at the edge of the sand, because of the fresh water flowing into the ocean from the White River, but once you get out a bit, the cooler fresh water mixes with the warmer ocean water, and all is irie!
Yes, many people take their floaties out into the ocean at SSB. The nice thing about the AN area at CSS, is that it is private, so you are not going to have people walking by with bathing suits on "gawking", and you are not going to have people with bathing suits on swimming into your area. It is just peaceful and private.
Take water shoes with you, though, as the entrance to the ocean can be rocky at times. We have been there when there are lots of rocks, and times when there are no rocks at all, it changes often. Regardless, once you get out into the ocean, the bottom becomes just sand, and is wonderful!! There's also a great pool, swim up bar, lunch grill and hot tub at SSB as well. It's the perfect place to be!!