I just carry a rifle.
So USMMA doesn't issue undies? What the heck is up with that?
The issue of rashes is a sensitive one (pardon the bad pun). The only place I had issues was between the thigs where the rubbed together when I ran and before I lost a little weight. I never had issues with tighty whities.
I suspect boxers will be more comfortable and "airy", which isn't a bad thing in the oppressively hot and humid summer at USNA. USMA, USMMA, and USCGA aren't much better. In fact, now that they are doing all that Sea Trials or whatever stuff where the Plebes crawl through water, mud, etc., boxers may be REALLY recommendable.
Wish a current (male) Mid would show up to help us.....