We have also gone to Hunting Island the week after Christmas and in the 3rd week of January for the Martin Luther King holiday several different times and found the weather very nice. It was sweatshirt weather, but usually in the mid-60s and would get into the low 40s at night. As far as I'm concerned, that's GREAT camping weather and perfect for a good evening fire in the pit.
We also use an electric heater to keep the 5'er warm overnight and the furnace set on 55 just in case it gets colder than expected.
The beach during the winter is so much different than in the summertime. It is great to walk and have quiet reflection time. Our dogs LOVE to go during the winter when they can play in the surf.
Hunting Island is near pretty much NOTHING! It's a 15 mile drive into Beaufort and the closest supermarket, but there are a couple of restaurants just outside the park as well as a fish market with fresh (just off the boat) shrimp. It's a great place to get away from congestion and so many tourists.
It's a lot of miles away, but we have gone to Gulf Shores, AL in December and it was nice and warm a couple of days, and then cool a few days. It was 80 and we went to the beach and even got in the water, then a storm system moved through and the highs were in the 60s.
2017 Ford F350 Crew Cab 6.7L 4x4 DRW