Have you thought of "borrowing" off of repaints of Microsoft Flight Simulator 2004 aircraft? I've personally downloaded over 10G of aircraft over the years, including some insane repaints. Viewing the bitmaps of the paintjobs gives you excellent graphics to port onto the model, and include all of the weathering that many of the designers include.
The OV-10A Bronco, for example, lives in my "Rockwell" hangar, and comes in paint schemes for Air Force, Marines, ROKAF, RoVAF, Venezuelan, and even a California Department of Forestry (which is how'd I'd repaint it).
Within FS2004, you can park the bird on the ramp, zoom in on the bird, and do a virtual walk-around. Screen shots [ALT-PRTSCN] pasted into Photoshop or Gimp can be edited for colors, pulling graphics, or just used as reference photos.
Some great sites to download free add-ons for FS2004 include:
... not to mention that the program comes with some pretty remarkable aircraft itself. There's a plethora of C-47s/DC-3s on the web just from this program alone. They've got the FG Piper Cub, Cessnas, and a Learjet that should make it's way to FG. As for the Ford Trimotor? Fogeddabowdit!
Ethically, is it plagerism? Maybe. Most designers post their email addresses in the text file for aircraft characteristics. Personally, if I was gonna lift a graphic (NOSE ART!!!), I'd ask the designer first. I know that if I was a flight sim add-on designer doing it for the sake of the hobby (hey, just like us cardmodelers!), I'd be pleased as pie to get a 3-D representation of something that only lives on my computer.
Phew! Okay, enough said, and I hope it helps us all out.