Bow ties and fezzes will always have a special place in my heart but as a literature student, the symbolism of the stetson just wins it for me. The Doctor wears it when it is time for him to die and when he is conflicted between what is right and wrong in A Town Called Mercy. I think it’s because it’s easier for him to pretend to be a cowboy, to give him the bravery to go through with it all. It acts as a sort of emotional armour, to keep him protected from being hurt when he is unable to admit that he is scared.
When he wears the stetson, he distances himself from the pain of his past; he is not the doctor, a man who is, in his eyes, the monster who leaves behind a trail of death but a brave hero of the west, someone who keeps going despite having every reason not to.