I love your idea. I wonder, if you do run into a paucity of information,whether you might want to consider expanding your concept of "art" to include writers. Your point, which is that work was chosen for the deliberate purpose of good public relations for the government agenda, might also be well-supported by looking at authors.
The other aspect that occurs to me is that it might be difficult to find much in the way of documentation of such a purpose, but that you might be able to establish your point indirectly, for example, by examining how much publicity was actually generated through the selection of such "visible" workers. Were there many newspaper articles? Were there press releases from the government? In those days, I think, (although I have no personal knowledge), the media were far more willing to be fed news from the government, with less critical review than we have today. How much publicity was planted to advance FDR's agenda?
I think we would all like to know more about this project as you move along.