Here is a trick of the trade that will help your marcher wave off some of the side effects of participating in a competitive marching band.
Deodorant/antiperspirant is your friend and your friend's friend. Please apply generously and often. This is one of those cases when a little does not go a long way. This is not a park and bark marching band. They are on the move. Sweat and repetitive movements can be a recipe for disaster. Did you know that deodorant is not only for under your arms? You can rub on deodorant before exercising on your thighs in order to prevent the dreaded marcher's chaff and to your feet to keep marcher's foot at bay. They are never going to be accused of being lazy, but now they can be fresh as a daisy.