I use a generous amount of ACF-50 on my Airstream on any parts which I feel may be affected by corrosion.
ACF-50 has a kit that is $30 from Aircraft Spruce or available on Amazon. I comes with a small spray bottle and a re-fill bottle.
It is viscous enough to remain on the surface until the next cleaning. It has also a purple hue, so it combines well with aluminum and stainless steel.
So far, it has proved to be a means of reducing corrosion and rust. I actually had the rear storage area, axles and the entire bottom of my unit treated with Corrosion X when I bought it.
I have the fortunate ability to store my unit indoors and since corrosion is a function of electrolysis, I also ground my unit.