The 72hour free transit for entry in Guangzhou

Hi there, I have already asked this question but would like some re-assurance.

I am a Lithuanian citizen (approved country). I have a single entry one issued in London to enter China.
I purchased my return ticket from London to Guangzhou but had some last minute plans to visit Taiwan as well.

I plan to land in Guangzhou and ask to use the 72-hour free transit to enter, and show them my outbound return ticket to Taiwan which leaves in 2 days of arrival. Will it cause any issues that the ticket is a return ticket back to Guangzhou? Would they force me to use my one entry one to enter?

Finally if this succeeds, flying back from Taiwan to Guangzhou I could then use my one entry visa to enter China, a week later I would catch my return flight back to London from Guangzhou.

Does this sound okay, would there be any issues?
I have contacted the Chinese embassy in London and they have said that the Chinese embassy in China has not confirmed any information about the 72 hour free transit to them, they don't even know if Taiwan is considered as a third country..

Before departure I plan to inform my airline of my plan to use the 72hour free transit, is this likely to cause any issues?

Where can I find the official explanation of the rules to print off and read for myself?

Appreciate your assistance.

Many Thanks
Mantas