As for adding the extra awning yourself, I would question whether there anything in that wall to screw into strong enough to support that "extra" awning. I can assume the factory provided units also have extra backing plates built into those wall sections just for the added awnings. Your wall sections most likely dont. The walls being made up of small aluminum tube, with luan and fiberglass backings laminated while strong doesnt leave you with much structure to sink fasteners into.