Can I use the 72 hours transit Visa?

We will be flying from San Francisco to Beijing - staying 71 hours - and then flying to Hong Kong. We are hoping to take advantage of the free transit. Our Beijing tour guide says they checked with customs and we fit the criteria - however, the San Francisco consulate that issues the Chinese entry permits says that we do not fit the criteria since Hong Kong is technically PRC. Where I like the answer of our Beijing tour guide since this will save us $500, I am incredibly nervous about arriving in Beijing and being told we should have had the entry permit. I would think the chinese consulate would know the rules?!

Do you think we qualify? How an I know for sure where I can take this trip and not be worried about this?