You must have mis-heard that. The very smallest travel trailer I've ever seen was 10 feet (a tiny 1960s Shasta Compact) and it's about the size of a walk-in closet -- and not a big one, either.
Even assuming the nine feet didn't include the hitch length, you're still talking about something comparable to a Casita 13
, in other words, very small. That's not Airstream's strength, so I doubt they are really considering something like that.
Maybe nine meters (28 ft)? Or "nineteen" feet (the Bambi)? Or maybe a trailer nine feet wide