As for S.C.... I at least hope we have not changed that much
If I was a LEO and were talking to a driver / occupant of a motor home, I would assume they have guns in there... where and how they are stored would not be important. If they ment me harm, I would already be.
As for Paris Island... let the guard at the gate ask the question. If they do, then declair it, If they don't then don't worry about it.
My father, One of the Chosin Few (or Frozen Chosin as some call them) by the way, goes to a local Army PX pretty often and they told him just to keep it in the car and don't carry it.