Welcome to the forums!
My first suggestion would be, DON'T USE ACID on your Airstream! I can't speak from personal experience but the conventional wisdom is that you can never neutralize the acid that gets into the seams and under rivet heads which will lead to leaks "down the road".
There is a large folklore on polishing Airstreams and several companies that sell the supplies. Here's one that has a lot of information on their web site-
One of the more popular polishing systems is Nuvite. This involves a succession of abrasives. You start by polishing off the oxidation with Nuvite F-7 or F-9 grades using a rotary polisher and then go to one or more finer grades (C & S) using a random orbital (Cyclo) polisher.
I used Nuvite to polish our first Airstream. I could afford to have a professional polish our current Airstream!
Some other polishes are recommended by others. I believe one professional aluminum polisher uses Mothers Aluminum Polish http://www.mothers.com/02_products/0...ml#&slider1=20
Our present trailer was polished by Mike Rice of Time Tested Restorations
and he did a fine job.
He uses Gord's Aluminum Polish. http://gordsaluminumpolish.com/
Good luck with your project, and as always--"your mileage may vary".