So, I’m going out on a limb here since I work at home and don’t bike to work. However, I have traveled significantly and here is one key I have found for wrinkles which will work for paniers or a back pack. Use dry cleaning bags over the clothes and roll or fold them in the bags. It reduces the wrinkles amazingly. I agree with OneEigth on the rolling thing. It reduces wrinkles and it takes up less room. But the bag will reduce the wrinkles even more and you already have them since they come with the dry cleaning! good luck on your ride.
