I wouldn't worry too much about staining. A Black UK, RK, Union Kilt hids a multitude of sins. I have worn a kilt doing plumbing, carpentry, electrical work. The only thing I don't do is paint, and I keep an old pair of jeans for that. The only one of my kilts that I have managed to stain is the carmel duc (Carhardt) UK, but it is a really light color to begin with, and has seen the most action work wise.

Adam