Hi, Gang: Maxxair makes a vent cover specifically for the Hammond vent  used by Airstream. Their standard cover is great but it does not allow full elevation of the vent itself; i.e., this vent, as you
know, lifts from one side and then the other until it is flat above the 14 x 14 inch opening. The standard Maxxair does not allow full elevation of the second maneuver.

You will also need the adapter which fastens the cover to the collar of the vent, so that you do not need to drill into the skin. I presume it is needed for the Airstream vent cover, also.

Ah, a breath of fresh air via Maxxair!

Donald