According to the manual for a 2018 Sport, a 22' measures 21'-8". Look at sheet 4-2.
My 34' measures 34'-11" overall.
My 25' measures 25'-11" overall.
To find dimension of any trailer, go to Airstream.com and click on the "Company" tab.
From the drop down menu select either "Manuals" or "Document Archive".
At Manuals, when the window opens select the year model of the trailer and scroll through documents looking for "Specifications" (the specs may be inside the manual for some specific year models). If you do not see a document there check the Archive.
At Document Archive, scroll through the documents. They are in year order, generally.
Look for "Specifications", where overall length is given, along with much more data.