I thought a while back while I was surfing around that I came across a vendor that sold different hatch covers for Airstream. Vintage Trailer Supply? I know it will probably bug me until I find that. I will look up your tread if I do. Now I believe it shouldn't be 'too' difficult to reproduce another one. Look in Search. There are some posts of members making hatch doors for new hatch accesses.
Neil and Lynn Holman
Kirk Creek, Big Sur, Ca. coast.
1966 Trade Wind
1971 Buick Centurion convertible
1969 Oldsmobile Ninety Eight