Instead of defining a default set of clothes per body plan, which would limit things to just one default costume worn and the rest carried along to probably never be used, you can define costumes in a separate part of the Noxico XML data and refer to several of them in the body plans. One will be picked out on generation, its component parts filtered out on physical feasibility (no pants if you’re not bipedal for instance) and even then there’s some degree of randomness available. For example, you could have the system pick between plain and lacy underwear (you know, for the ladies), even though those come in two parts. And since recently, you can also predetermine up to a hundred random tokens, which can be used very nicely for color coordination. So not only will both parts of underwear be the same style, but they’ll also have matching colors!
This does of course go for more than just undies.