Well, theres so many types of wings im not quite sure what could be possible for you all to do and maybe like 57, 255, 20 as the green. If i was to give you colors im not sure what they would be like.
You can use something like Photoshop / GIMP / Paint to get you the RGB values, or various websites like Adobe Kular.
I have an idea. What about a second set of combine wings that have a relatively short trail(1/2 or 1/4 the length of the hard server player trails) to make it look more like actual wings? Could it be possible to customize the color? Make them cost twice maybe 3x as much as the regular combine wings.