So back when I used to run a lot in the winter, like 20 miles wearing running tights, there was a very cold shrinking effect on the male anatomy dubbed popsicle effect by some runners. There were special undershorts with windstopper technology to stop the wind effect. A bread bag strategically placed could also help but not as comfortable.
So if you are back packing all day is this a problem for men, or is this not an issue since you are moving at a much slower rate and you need more clothing on to stay warm so your body maintains a more even temp across the entire body?