Presumably, the fun way of including this in an adventure would be not to spring it on the PCs as an "oh tough, you didn't know, we're locking you up" (or executing you a la Wesley Crusher in the TNG episode where he steps on the grass or something), but to clearly mark the clothing laws in customs inspections as they travel to starport, in signs at the gate as suggested, in library data for the world. The PCs make sure they're wearing requisite clothing and it all seems much of a nothingness.
Until at some point as a result of the adventure, the PCs need to shed clothing etc for some reason and have choices to make about who has what (assuming they've remembered the detail). Maybe they need to offer someone they've rescued some clothing to keep them warm or something.
Just thinking out loud. Hope it helps.
tc