This might sound silly and I suppose stands at odds with the general premise of the thread, but: Following the story's theme of building Asterion up and working to restore his agency and sense of self, is there a possibility of encouraging Asterion, when he's ready, to choose his own appearance, find his own style and maybe even surprise the MC from time to time? We've had a small moment of him doing so in Chapter 18 which was nevertheless great to see.
I always end up sprinting through the dress-up without changing anything outside of his preference because I don't want the MC to continue to exercise that kind of power over him.