Sounds a very similar product to POR15.
I used POR15 on my Hensley hitch and Classic A frame year or so back and it came aout well.
I top-coated both the hitch and the A-frame after the POR15 because of the UV issue mentioned in the POR15 in the instructions.
To topcoat the Hensley, I found a rattle can orange rust paint that was a pretty good match to the original Hensley Orange.
For the trailer itself, I had a small amount left in a spray can of Airstream "Pewter" orignal paint. I took a sample to our local hardware store and they had teh equipment in their paint dept. to mix up a matching rust paint.
For not much more than I paid at JC for the spray can, I got 4 litres of the custom paint and carefully brush painted the A frame.
Probably not as nice a finish as if I had sprayed it but a whole lot easier without all the masking to do and it looks fine - got a lifetime's worth of touch up paint now too!
Brian & Connie Mitchell
2005 Classic 30'
Hensley Arrow / Centramatics
2008 GMC Sierra SLT 2500HD,4x4,Crew Cab, Diesel, Leer cap.