I guess I can just copy the lines I have and paste them one pixel shift. This is gonna be tough. Maybe I will practice on the rudder first.
I assume the 190 aileron is not NSEW.
You assume correctly about the 190.
You don't need to shift the panel lines. You just need the free select tool and trace a rectangle with one long edge over the panel line that separates the aileron from the wing. Then fill the rectangle with a gradient, and reduce the opacity.