Jay, I just spent the last few days going through the pages of your incredible build. Fantastic work!!
I am so glad you decided to skin this bird!
Your issue with the rocker arm is unfortunate but all part of the compromises we must make working with thicker materials then originally used.
Regarding the use of etching primer; I did some tests on brass for a model I am building and Rust-oleum failed the scratch test after being top coated. A number of other box store brands also failed. I had excellent results with an automotive brand by Eastwood. Only downside is the need to top coat within so many hours. It is in their instructions but I am not sure yet what the results would be for a model if I waited longer.