This came up between myself and my wife while watching Outlander. She mentioned they never wore anything under their kilt and they rode for days on end sometimes which got me to thinking about the state of their 'manhood' for lack of a better word. I mean, if this is true, wouldn't they be heavily damaged or at the least calloused like concrete?
They wouldn't have worn kilts for riding horseback, they would have worn tartan trews for riding. The idea of riding in a feilidh-mor isn't well supported, and honestly doesn't not seem smart. Common highlanders would not have been able to afford a horse in the 18 and 19th centuries, and the Highland gentry that had been able to afford one would wear tartan trews for riding. Trews would offer protection to the inner leg that a kilt, without anything underneath, cannot provide. Kilts would be impractical. Just remember it's TV.
How is that show, btw?
I would check out albannach.org with Matthew Newsome for more information. He's one of the few kilt historians out there, and his work is top notch.