Your technique is interesting however you should shoot the Milky Way and try it and see how it affects the overall color. As you might find you are really removing a lot of color, but maybe not depending on how narrow and how close you are getting to the light pollution spectrum. I have found that light pollution is more greenish than yellow, here is a picture showing some of the light pollution that I get even at somewhat remote sites because of all the large cities:
MW-start-end by
Alan Smallbone, on Flickr
As a side note in this image you posted you cannot tell if you have still have star color or not. Vega is most likely already blown out and lacking in color, and it is white star anyways. A better choice would be something like Antares, which is a yellow-orange star and or Betelgeuse which is now coming up in the early morning skies.