Back in the day most fender storage I saw was done using finger racks which was usually a metal rack with wood "fingers" on the vertical. The fender (and other panels) would rest on the rack while leaning against the fingers. Personally I wouldn't think you would have a problem however you store them unless you're planning on leaving off of the truck for a LONG time.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.