There are two toilets on Chinese trains - one on each end. At least on the sleepers, one end is a squat toilet, the other a sitting one.

Dear LostinChina: You are thinking too much and it will only add to months of anxiety before your trip. Remember a China trip is an adventure, sometimes you just have to hold your breath, shut your eyes, grin and bear it, and go with the flow, no pun intended.