Will this scenario work for my wife and I and qualify for the 72 hour rule in Beijing

Our flight from Bangkok arrives in Beijing on March 30 at 15:50 in the afternoon, and our return to US departs 3 days later on APril 2 at 17:20 .. that is actually 73.5 hours, but I am thinking by the time we get through customs upon our arrival in Beijing, and the time we check in at the airport for our return flight to US (at least two hours before the flight), it puts us under the 72 limit. Will this work? we have secured hotel reservations and negotiated a tour guide for visit in Beijing. We have valid US passports well beyond 6 months.