I have recently been thinking of doing a similar thing next year so it would be great to here how you get on.
Aside from my full time job I have been working for an agency that offer flexible hours for private students and groups of students. I feel that there is enough work for you to live off if you look around/advertise.With regards to pay (from personal experience) private tutoring can be anywhere between 150-300rmb per hour. There are a lot of small time companies in Chengdu offering last minute teaching work with very little effort.
Hope it goes well for you.