Hey Todd,
Let me share with you what I've been doing for the past few years.
In North Myrtle Beach, I have been flagging down the beach patrol officers or getting in touch with them through the lifeguards. I explain where I'm staying and that I want to put my boat out there, etc. For the past 4 years they have been VERY accomodating, as long as I followed their rules. With my assurance that I would, I was allowed to drive out on the beach and drop off the boat, and sometimes the trailer for the week. (I think the trailer was determined by the relative beach width at high tide.) As I recall there are only a couple of major rules different from any other beach goer.

1-Drive on the beach ONLY with their permission, which meant they were there to escort me too.

2-Coordinate with the lifeguard when negotiating the surf to keep the swimmers safe.

3-Put the boat where they tell you so the beach clean-up personnel that come through about 4:00am aren't complaining. Remember, these people drive BIG equipment that can tear your boat up really good!!! Keep them happy!!!

Myrtle Beach used to have a permit required. I'm not sure of that one though. Their office of Public Safety should be able to put you in touch with the beach patrol for the area you are in.

Have a good time

Rich