Flight with separate airline but want to enjoy the 72-hour visa policy

I am currently in China and have a single entry one, but want to visit Singapore without having to change my flight home from Pudong to Dubai.

Am I right in understanding that if I do so, when I return to Shanghai from Singapore I can go through passport control, collect my bag, and then re-check in with a different airline for the flight to Dubai a few hours later without issue, providing I have proof of my onward flight to Dubai? Or is there some sort of different procedure which applies to this?