We have never stayed there during February, but have gone to Hunting Island, which is about 50 miles north. Take a light jacket, since you may have to deal with a COLD wind coming off the water. The night-time temps can get quiet cool and if a cold front comes through, it can be downright cold (down around the freezing mark), so make sure you have some propane and especially a good heater.
If you happen to be there during a warm time, temps can be in the high 60s and low 70s, which can feel pretty nice.
Mosquitoes shouldn't be too bad during that time, but make sure you have some bug spray, just in case. My son was there camping for a couple of days the first week of January and said the skeeters were pretty bad, especially for the winter.
A good campfire in the evenings should be very welcome.
Have fun, we like that campground a lot and enjoy a trip into Savannah for seeing some sites and on occasion, grabbing some food at one of the local eateries.