Master Shu would be wearing a "cangue," which is a "heavy wooden yoke borne on the shoulders and enclosing the neck and arms, formerly used in China for punishing petty criminals." In Chapter 11, Moxa warns Prince Jen, "Don't go near. He wears the cangue, the Collar of Punishment." Make sure the "magistrate's seal" is visible; the cangue was thusly marked so that if the seal was to be broken by anyone, it "means a death sentence" for the person who tampers with it.
If you are doing makeup as well, consider also that Shu face is "blistered and sunburned." Place him in drab, loose robes to complete the effect.