How big is this pastel (in grams). 1 rat fuzzy every two weeks is next to nothing.
Are you sure he's that fat? A BP that got so fat eating two rat fuzzies that he would need to be put on a diet seems...rare.
For the shed you can try doing something like soaking him, then covering him with a wet dishrag or towel or something. While he's climbing out from under it he'll rub against the towel and hopefully rub the skin on his head off. People also put the snake in a damp pillowcase with great success.