I'm glad you've gone into detail on how it's possible to live a good life in a third-tier city of a poor province of China off of 3500 Yuan/month. Unlike you, too many posters on here are trying to give the rest of us a false impression of the buying power of an FT's salary. I hope your post will help silence them.
Your particular employer must be delighted at hiring such a conscientious FT for a relatively low salary. I've always said 4000 a month is the lowest I'd accept for a 16 lesson a week stint at a public college/university in a Chinese backwater place. But I've loads of teaching experience, a bachelor's degree and a teaching qualification. I suspect you'd be on 4000 or 4500 if you had a proper degree. The other thing about Sichuan is you can teach there without a Z visa in a backwater place without worrying about being nailed by immigration. Be fully aware the local police will know about you if you are doing so, but will turn a blind eye to that. Likely they'll be on good terms with your university. Just don't attract attention to yourself by getting into a fist fight in the street, or something like that, and you'll be left alone by the authorities. Finally, I agree with you that Turnoi is a trip.