This video explains a specific platform that Andrew Laszlo and his team built to shoot the "close-up" scene between the deputy Galt and the pilot.
As you will notice in the video, there are no tourists. It was 6am when I was there at Othello tunnels. And the area was closed to public. Rocks was falling at the Rambo cliff.
A big gate was blocking the entrance. Well, I passed the gate...whatever it takes for the Rambo fans!
BTW, there are rare photos of Deputy Galt in this video.