I think duck cloth was a good choice. That seems to be what Utilikilts uses for their Workman model, which I love, although I'm not sure about their other models. I can wear mine all day and while you will be able to see that the pleats have been crushed or sat on, they won't get too terribly deformed-looking. UK does stitch the creases in the pleats, though, for reasons mentioned earlier in the thread. So you'll probably end up needing to do that.

Good luck, and I can't wait to see pictures!