I'm in Georgia so legality isnt an issue. Although Im not sure of the laws in NC and SC and I would likely be traveling between them as very close to both.
I may look around at some current designs and see if I can mock something up. Im picturing either something that mounts horizontally on the trunk door or vertically behind one of the back seats. I know there are a few racks for law enforcement, one of those might be a good starting point.