Hi, Joe,
Like I said before, it is not possible to judge the exact color in a photo. The color is affected by the color temperature of the location, the camera used, film type(if it is used instead of a digital camera), the setting of the camera, as well as the color profile and color management system of the software.
I do some calibration to the images you posted. Of course without a reference I can't do it very exact, for example, the photo with the Rover still looks too redish to me,judging by the faces. If I reduce the red too compensate for the color of the face, then the car would not be so orange. (the problem is, I don't know the real skin tone of the 2 gentlemen, but I guess it looks too pink for someone in the field)
Besides, the color looks different when you view them with different softwares, and with different monitors or display cards.
But anyway, from the photos I've seen and the image files I have examined, I agree Tamiya XF60 should be quite close, when mixed with lillte white or pale gray. Another way is add some yellow to sand.