I worked for 30 + years for a company that "acidized" things. I would think that it would be very risky to spray anything with an acid ph on your Airstream. I don't know for sure, but I expect, that the aluminum that is used on a tank trailer has been formulated/processed to be chemical resistant, which of course, an Airstream hasn't.
On the other side, caustic (alkaline) liquids will desolve aluminum, so for sure wouldn't want to put any alkaline ph liquids on an Airstream surface. Would be a good way to strip one though.