RUSH at most Chinese missions usually means next-day service. If you get your application in morning of Day 1, you should have it back by afternoon of Day 2.

Given the way the nonstop flights SIN-PVG are scheduled, it looks like you'll either be 29 hours (therefore a no-go for you on TWOV) or to stay within the 24 hour limit, you'd only get a couple of useable business day hours on Thursday afternoon, once you figure in transfers to the city from PVG.

Getting a visa is your best option, especially if company is paying for it.