Hi Doug, I don't do anything terribly special in regards to that issue, other than with the stenciling (where it can cause the worse-looking results). Otherwise, I just try to avoid showing too much of that in the screenshots I take by controlling the lighting/angle.
The root of the problem is of course the contrast in the green and blue channels of the complete map textures, between the values used for the bare/polished metal and the values used for the paint - the greater the contrast, the more borderline shows up in the sim. For the stenciling, which fortunately should already have a rather dark grey value in the complete map green channel (due to compressed paint application/low paint scatter), their grey value in the green channel is not unlike the darker grey values used for the polished bare metal - this, therefore, already reduces a lot of that potential contrast in values. For the stenciling in the complete map blue channel, which should technically be a fairly dark value (being paint and not metal), I make them fairly light/not too dark when contrasted with the full white value of the metal in the blue channel, so as to try and prevent a too-harsh contrast.
Fortunately, that border that can develop in the textures in the sim, between the paint and the polished bare metal, I've actually seen on real aircraft as well, where they've masked the markings prior to polishing the metal, leaving a very slight boarder of lighter/duller metal around the markings.