You may also consider this for your panel lines:
Make one layer in a dark color, like black. Set the transparency level so you get more of an impression of the line than particularly obvious. Copy and paste this into a new layer, and invert the color so it's white. Move this one pixel towards the forward or leading edge, and one pixel in or out. Which direction you move it will depend on your vantage point from the cockpit.
IE, for the wings, I move the "highlight" layer one pixel outboard, and then one pixel forward. Anything aft of the cocking I move a pixel aft, etc.
Again, set transparency so your highlight layer is more implied than obvious. Remember, panel details are MUCH more subtle in the actual aircraft than is implied by many skins.
Use this same technique with your rivet layer, as well.
When I get home I can post an example from my F4U template to show you what I mean.