The military Staggers were essential civilian ones in military colors. These aircraft were the commuter aircraft for senior staffers. The US Embassy used them in many countries around the world for their travel needs.
Modifications were primarily radio equipment and possibly upgraded instrumentation for IFR flight.
How about doing a clear one? This one was at AirVenture many years ago. It was covered not with doped linen but modern clear synthetic film. The other is an Embassy ship.