Also, China may have been lax in the past but it has become increasingly more efficient at enforcing labor and other regulations both upon its own citizens and over foreigners as well.

Never moonlight.

You run the risk of deportatarion for tax avoidance if found to be moonlighting without paying tax on your second income.

(Case in point greedy FTs in Hainan employed by the public sector caught teaching and avoiding tax while moonlighting at language mills.)