Teemack, earlier Airstreams had aluminium wraps, and more recent trailers used plastic. Wherever the aluminium skin touches the steel frame, there is the likelihood of galvanic corrosion. This can be minimised by the use of non conducting gaskets or paste (e.g zinc chromate) between the two dissimilar metals. Although your method could be made to work, I would prefer to strip out all the wraps and get a skilled welder to repair the damage. While the wraps are off you can rust proof all the visible frame members. After using a good rust-proofing paint system, you will have preserved the trailer for another generation, AND you will know you've done a great job! Nick
Nick Crowhurst, Excella 25 1988, Dodge Ram 2500 Cummins Diesel. England in summer, USA in winter.
"The price of freedom is eternal maintenance."