I stayed in PVG for 3 days with the TWOV before hopping to BKK with a confirmed ticket. I'm just going to wish you luck because the chinese customs personnel don't play around. They even requested to see the hotel confirmation and asked me what my plans were while staying there. It took them ten minutes of checking papers, asking questions and looking at the computer to finally let me through. I was thinking about getting a 10 year visa so I could non rev through PVG every time I would visit any other country in Asia but I don't know if that can even be possible