If you find a donor trailer, 1965
exterior "five-panel" endcap segments are interchangeable, number to number. The rivet holes and panel edges of used segments may not align.
I have spoken to "Inland" on the phone, who offers an Airstream Factory produced universal segment of unspecified grade that is oversize, "one size fits all", exclusive to the narrow body five panel trailers. About $400 ea.
The latest version of Harbor Freight's English wheel, $225 with coupon, is more than adequate to iron out mild damage. There are encouraging threads on this Forum using the English Wheel. Visit the youtubes as well. It's not rocket science.