I feel out of place in that I have a legitimate suggestion, but here goes anyway . . .
Try groin guards designed for martial arts - Blitz manufacture a good one in the UK, so stands to reason the US probably have zillions or brands, varieties, fur linings, etc.
Looks like a big pair of undies with "jock" type straps, and believe me, when you are teaching kiddies who are about half your size roundhouse kicks, you (and your potential future offspring) will thank you. They are designed to be less cumbersome and not shift around despite the user throwing themself (or anyone else) around a lot.
They also make a great "thwack" noise when hit by a paintball, guaranteed to raise a few eyebrows . . .