If there is a covered 14 inch square hole in the middle of the roof, you had an AC at one time. Regardless, if you did not have one up there, the Airstream was prewired for one. A drain line will have to be considered....not a major deal but does require some work.
"If it can't be reduced, reused, repaired, rebuilt, refurbished, refinished, resold, recycled or composted
then it should be restricted, redesigned or removed from production."