Transit visa on arrival for 72 hours

I have booked a ticket for LA from Dhaka with China Eastern. On the way to LA, I will take stop over in Shanghai for 72 hours as transit passenger for a city trip and being holder of an Australian passport, it is okay not to obtain prior visa from Dhaka. But the problem now that China Eastern will land to Kunming first and they do not have connecting flight to Shanghai on the same day. It means I have to clear my luggage and go through immigration to catch the next day morning flight to Shanghai. If this is the case, then I have to take on arrival transit G in Kunming and I will loose 1 day out of 3 days and I can stay 2 nights only in Shanghai but I want to spend 3 nights in Shanghai on the way to LA. Is it possible to obtain transit G on arrival in Shanghai instead of Kunming if I stay in the Kunming airport all the night without exit and catch next day early flight? Please advice.