Yes, you're correct about needing to watch for collateral exposure, however that applies to any swimsuit not just g-strings. For example, see-through boxer trunks could be deemed illegal if the genitals are plainly visible.
Regarding g-strings, the chief justice in the case you site made it abundantly clear regarding the legality of g-strings and thongs under North Carolina statutes. The language from page 3 is below. Here's the link:
http://academic.cengage.com/resource_uploads/downloads/0534619509_37754.pdfBTW, the county police passed by 4 times last weekend on Bird Island, each time I was wearing a g-string. He didn't say anything to me but gave a warning to a woman who he spotted topless.
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"We have already concluded that the phrase “private parts” includes the external organs of sex and excretion. On the facts of this case, it is unnecessary for us to determine what, if any, other parts of the female or male anatomy may be included within the phrase “private parts,” as used in N.C.G.S. § 14-190.9, in light of the legislature’s expressed preference for an “expansive” interpretation. However, given the posture of this case, we think it wise to note our agreement with the conclusion of the majority below that buttocks are not private parts within the meaning of the statute. To hold that buttocks are private parts would make criminals of all North Carolinians who appear in public wearing “thong” or “g-string” bikinis or other such skimpy attire during our torrid summer months. Our beaches, lakes, and resort areas are often teeming with such scantily clad vacationers. We simply do not believe that our legislature sought to discourage a practice so commonly engaged in by so many of our people when it enacted N.C.G.S. § 14-190.9. To make such attire criminal by an overly expansive reading of the term “private parts” was not, we are convinced, the intent of our legislature. The difference, however, between defendant’s conduct and someone wearing a bikini is that the former is a clear-cut violation of recognized boundaries of decency, which the statute was intended to address, whereas the latter is a matter of taste, which we do not believe our legislators intended to make criminal."
