If I am out on my bike for a few hours then I don't bother to pack a kilt(s).

If I am going on a longer journey then I pack it(them) with my other luggage but I use a different method than most.

I fold the kilt into two with the pleats behind and then into two again. I have found that this means they can be neatly carried and I have no wrinkle problems when I take them out at the other end.