Yup, i was looking for that section a few min ago but got busy writing tickets... but as long as you prove you are from SC the ticket will never stand in court. The trailer is an extension of the vehicle when it is attached. If the vehicle is registered in SC, then the trailer falls under sc law... If the vehicle is registered in NC, then it has to have a trailer tag...
Here is is from NC code of law, the very first one.....
http://www.ncleg.net/EnactedLegislation/Statutes/HTML/BySection/Chapter_20/GS_20-51.html
The following shall be exempt from the requirement of registration and certificate of title:
(1) Any such vehicle driven or moved upon a highway in conformance with the provisions of this Article relating to manufacturers, dealers, or
nonresidents.
So that basically states that "non residents" do not have to have a NC tag on their trailer... Which states that it falls under the Origin states laws... So if SC doesn't require you to have a tag, then NC won't either as long as you are not a resident...
BUT, some a s s hole could still try to write you a ticket... but it will be dropped promptly upon talking to any judge on the phone even...