I've made the trek to huntington state park jetties it's nice, but not worth it if you don't go about 2-3 hours before high tide. Which can be inconvenient in the summer. The walk seems to take Forever. And honestly if your staying in Apache (near North Myrtle) your better off going to Ocean Isle to Surf fish. It's in NC, right across the state border. Of course that means you have to adhere to NC regulations and fishing license, but as long as you have a phone with internet and a Wal- Mart near by you'll be fine.
Bottom line. SC: best surf fishing spots are Garden City point (sneak pass the guard shack by parking at yucca and walking beach), Pawleys Island (was out there yesterday only caught some flounder), or Georgetown beautiful sprawling beaches and no one out there, but it's a drive. NC: ocean isle or Calabash.
Best advice I can give you since it seems like your doing your research. Use Bing maps (not google earth) and research some locations. Bing uses actual photos taken by airplane pilots where google earth is satellite. Trust me compare the two the difference is unevlievable. Mess with the compass once you find a great location. The different angles will help you gage the depth of the water your fishing, if any structure is there, and if the location is worth a damn honestly.
If you want convenient just stick with the crowds on Apache Pier, or find a spot on the marsh near a large mouth or tributary. Use local live bait. Shrimp is best, minnows second, cut bait last (not frozen its mushy and worthless). I mean bloody cut bait. Popping cork with shrimp on a slack tide. Flounder rig or triple swivel for tide changes/mid-tides.