Maybe you should try something besides nylon? Something natural like silk, or merino wool? I ordered a pair of 150 gram merino wool Icebreaker under shorts. Anxious to see how they work. Never had this problem myself, but I swear by breathable fabrics and layers for many uses. When I'm riding, for long distance I wear leather, and locally I typically wear jeans. Long distance could mean 12 hour (or longer) days, "local" could mean anything from across town to up'ards of 200 miles or more. I've worked in heavy industrial environments for over 30 years and never had to deal with Monkey Butt... lucky me, eh?