When I wear my kilt (SWK 8yd acrylic), I always, always, always wear compression fit UnderArmour heatgear under it all- boxers and a compression fit shirt. It works miracles and is well worth the money, even in humidity. And trust me, I know about humidity. With that stuff on, I can traipse around all day in a full kilt with wool hose and neither give a care nor leave a sweat spot. I actually usually end up getting a little chilled. And, of course, in cold weather, I just wear coldgear UnderArmour, which keeps me jubbly bits warm no matter how drafty a kilt can get.