Do you coat your alpacas?

Our weather lately has been torrential rain followed by freezing temperatures which amounts to our animals being soaked to the skin! Even though we have a small structure for them to go into, they seem to still stay outside unless it gets windy with the rain and cold! Does anyone coat their animals to keep them drier? Last winter i put a heavy coat on one of our thin girls and she was like Houdini getting out of it! I was thinking maybe a light weight waterproof one might be better. Would it damage the fiber and cause it to felt? I'm just afraid they'll get sick being outside in the cold and wet with no where to really dry out at this time of year!! I was thinking about how some sheep are coated. Has anyone done this?