Hi Vraciu,
This is a superb reference photo - wartime color is pretty rare, and its also a close-up that shows a lot of detail about the plane/skin.
I understand what you mean about the stretching on the leading edge of the wing - the P-38 is the same way, very difficult to work with and trade-offs must be made. Have you tried painting the leading edge of the lower wing surface with an olive drab line, feathered into the grey of the rest of the lower wing? This would move the boundary between upper and lower wing colors down slightly from the midpoint, but it would look so much better to have a feathered boundary between the drab and grey than the hard boundary you have now. (IMO)
I don't see anything wrong with using some artistic license when the skin cannot support the 100% accurate look. Take a look at this example:
This artist has the leading edge of the wing entirely drab, and the feathered edge occurs on the lower wing.
The other great thing about this reference photo is the oil stains and smudges it shows; the color variations in the olive drab - from the sun-faded upper cowl to the more brownish drab of the side of the cowl, and even the two-tone grey near the panel with the drilled-holes. Look at the stains and smudges in the wing root area - what an outstanding example to follow of real world wear and tear. Bless Howard's photographer!
This looks to be a hard-used aircraft. You could really spend a lot of time on paint wear/fading, oil smudges & grime, paint chipping along access panels, if you wanted to. You've picked great subject there.
Couple other things I wanted to mention- and I just discovered this myself when looking over some old P-51 skins I did but never submitted. The horizontal panel line on the cowling above the exhaust manifold - it should be parallel to the centerline of the manifold - i.e. maintain a constant distance between panel line and the top edge of the manifold - yours looks to have a greater distance at the forward edge of the manifold. This could be a trick of the view perspective on your picture though - but you might want to check it out.
Also check the location of your gun camera port - it looks a little low to me, compared to the reference photo.
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