If your union can't help you with this, and your principal turns a deaf ear, try your PTA President perhaps he/she has clout. Let them know that in light of the fact that you are running yourself ragged, your students will suffer because you can't give them quality time in any shape or form. I have a saying that I have stamped on a bracelet "there are no victims, only volunteers", to remind myself that I can change my circumstances, even if it means looking for a new job. (The least you can do is STOP art club, and hanging art on bulletin boards, and all the extras you do. When queried, you tell the truth, YOU DON"T HAVE TIME). As long as you do all of the things you do, and do them competently you will be expected to do them. I know this flies in the face of logic of a professional art teacher, but you are not being treated like a professional art teacher, so until you are, then just be a human being and try to survive on your own terms.
> Anybody got any ideas to help me plead my case?