I just now remembered to mention to you that they had him write the novelization of "Indiana Jones and the Kingdom of the Crystal Skull." I am putting off reading this one, because (1) I rarely enjoy movie adaptations novels (2) I don't think this movie was that good. I will probably read it after I have read everything else by him that I can find.
If he had some latitude, he could explain the savages and primitive culture in his novelization of Kingdom of the Crystal Skull. He could add a backstory that made them believable rather than unbelievable.
For more on the subject, see The Best Indian Books.