I would not use it on an Airstream. We use it on our aircraft fleet and after an application the stuff weeps out of every seam, attracts dirt and makes the aircraft look horrible. The painting faculty we use will not paint an aircraft that has been treated for at least two years. It is an effective product but sure makes a mess.
I have tried ACF-50 on aircraft and it did not work well. I tried it on an old Beechcraft Bonanza, and it did nothing to slow or stop corrosion. It has the useful life of WD-40, which is to say about a month at most. It is expensive, over-hyped, and marginal at best.
Visible areas of your trailer would be better protected with paint or clearcoat, and non-visible areas could be sprayed with zinc-chromate primer - which really does work.
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