My best suggestion is to go to the Zip Dee site. A great item from a great company. If its to spendy for you...look in the classifieds here for a parting out Sovereign
(for length.) There is always an awning on Ebay which may work. The vintage style will be to unwieldy at that length. Out of doors mart has various parts too.
"If it can't be reduced, reused, repaired, rebuilt, refurbished, refinished, resold, recycled or composted
then it should be restricted, redesigned or removed from production."