2010 Lance 830 rear queen bed foldout issue

The contact point (edge) where the fabric portion of the rear foldout attaches to the camper frame, is a sewn in (silicon I think) piece of trim. It is deteriorating and in need of replacement. The trim is longer on one leg than the other. If looking "in line" at the trim, it's shape is of a hook. This trim laps the fabric edge with one leg longer than the other. It is sewn to the fabric through the longer leg portion of the trim forming the hook shape. The hook shape facilitates the attachment of aluminum straps that will be screwed to the fold down door. One edge of the straps tucks into the trim "hook". When the aluminum straps are screwed back into the door it effectively holds the sewn in fabric and trim to the camper fold down door. As owners of this model are well aware, this model has been discontinued and spare parts are all but impossible to source. So far our search for the type of trim we need has been failure after failure. 
Is there or a source where such materials such as this trim can be found? We have been to multiple RV centers who perform repairs and are told they can't help us. We have also been to multiple awning makers and upholstery shops but to no avail. 
Any help in our pursuit would be greatly appreciated.
Thank you!