The fender skirts on our 2011 JayCo are all attached on top with 2 screws each to the plywood floor (I'll be adding more), but the bottom of each skirt is attached to 2 thin arms with a self tapping screw to the skirt. This past trip while driving in a crosswind my wife noticed the skirt flapping in the breeze. The self tapping screws had worked themselves loose over time and the wind ripped the corner on the back of the skirt. We quickly pulled over to the shoulder on a busy interstate and hastily removed the one remaining screw and threw the skirt in the back of the tow vehicle. When we arrived at our destination I found that another screw was missing on the other side of the trailer. I counted and in all there were 13 self tapping screws holding the skirts in place on our 26 foot travel trailer. I went to a local hardware store and purchased 13 sets of bolt, 2 washers and Teflon nut and replaced them all. The replacement skirt was ordered (not under warranty), but it's rough cut and I'll need to spend some time cutting and fitting it correctly.
I commented on this problem to the local dealer who wasn't very interested in hearing my complaint. I went to the lot and the new trailers with skirts have the same self tapping screws holding them in place. Apparently JayCo hasn't addressed this issue yet.