Mine doesn't have a sticker, but that's where my tank is. It's right underneath the generator cover (if you don't have a generator, then it's just an empty bin).
Congratulations on your purchase!
Too bad about the manuals...kind of. Mine included the installation and user manuals for every appliance in the camper, which are helpful to have sometimes. But the Airstream portion of the manual is chock-full of erroneous information that just confuses the issue.
1995 Airstream Classic 30' Excella 1000
2014 Ram 2500 Crew Cab with Cummins 6.7L Diesel
Sold but not forgotten: 1991 Airstream B190
Sold: 2006 F-250 6.0L Powerstroke Supercab