72 hour visa, how to count the layover time?

Hi all,

I have a long layover in Kunming, Yunnan, that lasts 85 hours. This is very close to the 72 hour free transit, but just over the limit. Does anyone have advice on whether there is some leeway/flexibility on the 72 hour policy. Or if I'm going to stay for 85 hours should I go ahead and try to get a tourist L type entry permit?

Thanks,