"I will not teach illegally on a tourist visa, or anything else like this"

Well, really it's not much different than what you are doing right now really, which is teaching with an "illegal Z visa". (Chinese law requires a bachelor degree to be a foreign expert, and qualify for this visa, your school was able to break the govt law and get one for you anyways, but technically it is still illegal and if anyone in gov knew or cared (they don't), it would be revoked.) With the current climate in China, I would just be concerned with having "any" visa, and then doing whatever you feel willing to try afterwards.