We winter, Jan - March, at Pioneer RV Park, Port Aransas TX. It is a great park, located at the north end of Padre Island, (Mustang Island) great activity center, with an activity director. The park is very popular and reservations are a must. With prior approval from the activity director, I believe the activity center can be used. I don't know what kind of "get-to-gather" you have in mind. January tends to be a bit cool, however any given day can be good or not good (no day is really bad).
Of Note: There is a State Park on Mustang Island. We have not stayed there, but drive by it very often. It is within 500 yards of the Gulf of Mexico. The sites do not have sewer, but do have electricity and water. Also, one can camp on the beach, no water, elec or sewer. It works for many people for a short time. You can drive the beach for miles - no private beaches owned by condos, etc. Below Mustang Island is the National Seashore which is in fact a National Park. No private buildings, no condos, etc. A LOT OF SAND. After a few miles down the National Seashore, only 4 wheel drive vehicles need go. Surf fishing is available all along the sea shore.
Port Aransas has a number of fishing charter boats. Port "A" has 3 stoplights, one grocery store, a ton or T-Shirt shops - got the picture, a small fishing village. You can get to Port "A" either by land from the south coming up Mustang Island from Corpus Christi or the fun way, by one of the 5 ferries FOR FREE. Watch the Dolphins play as the ferry crosses from the mainland to the Island. Yes, we enjoy the area.