You're really put much into this shed thing. The moss isn't needed. The snake will shed, if your husbandry is correct, you don't need to do anything special for the shed. You're just worrying over nothing. Take a breathe, this shed will happen. The snake will be fine. If for some reason the you have an incomplete shed, just soak the snake for 10 minutes then run your hands over the stuck shed.
Good Luck!
Jim Smith