So, you're saying crotch-leg 2 has a separate material entirely than crotch-leg 1? I'm not familiar with UDIMs so can't speak to that part of your story, but for a traditional workflow, the 0-1 space (the lighter gray square where most of your UV elements are) is the only space that gets unique texture information-- it…
if the above was not enough, here is a good app to find what kind of gear to wear depending of the temperature and weather.. http://www.runnersworld.com/cda/whattowear/0,,s6-240-325-330-0-0-0-0-0,00.html