This is a long-shot, but a possibility. You might try contacting Arlene Fowler of Fowler Interiors (Symsonia, Kentucky). She specializes in refurbishing the interiors of Airstreams and is very knowledgeable about the upholstery fabrics used. She may be able to link you up with the fabric that you need. The Fowlers are regular advertisers in the Blue Beret, and can also be found through a "Switchboard.com" search.
Good luck with your upholstery fabric search!
Kevin D. Allen
WBCCI (Lifetime Member)/VAC/Free Wheelers #6359
1964 Overlander International/1999 GMC K2500 Suburban (7400 VORTEC/4.11 Differentials)
1978 Argosy Minuet 6.0 Metre/1975 Cadillac Eldorado Convertible (8.2 Liter V8/2.70 Final Drive)