Sorry for the lack of responses... Did some more researching, did some more skinning, and in between got busy, but never gave up on this.
As in this photo of a plane from the same group and from the same month as my Silsbee skin:
We can see for sure there has to be an outline around the stars and bars. On the fuselage, it could either be an outline or perhaps a painted over area of what used to be an outline.
However, we can see the wing, and there appears to be a faint outline (look closely, I can see it, it displaces the camo pattern) around the star and bar on top of the wing. It cannot be blue, as it is a very light pigment. There MUST be an outline around the white in the bars, but it isn't blue.
Given the time frame, given similar aircraft in the same theater with red outlines, given how red color can sometimes look very pale in black and white photos, as seen here: (for example)
You can see how the red and white stripes on the tail are almost the same.
Given all of this info, and more, I have gone with red outlines. I'm 99.9% sure this is correct. As a coincidental note, it also matches the model his son built with "inside info" -- which had red outlines.
Added fin flash (seems like similar craft have them, so included it)
Desaturated the camo colors a bit, which ended up changing the shade of green (for the better?)
red outlines
resized upper star-and-bar to proper size/ratio