So I put a rack with some squirrel hides on it on a sled to get it out of the way for a bit, and forgot about it doing something else, and when I got it off again the hides were dried. I also checked it with fish, and the fish progressed too when on a sled. (The fish on the drying rack that is.)
So it seems like things dry on a drying rack while in a sled. This seems potentially abusive as one of the features of racks is the space they take up. The sleds are very compact, and all.