Can I get a visa to visit China without an airline ticket out of the country

Hello, I will be in North Vietnam in February and want to visit the Yuanyang Terraces in Yunnan. I want to take a bus from the Lao Cai - Hekou border of Vietnam and PRC to Yuangyang and then after 4 or 5 days return to Vietnam. Is it possible to get an entry permit to do this? Will I need proof that I am leaving PRC? Would a bus ticket be accepted? Thanks for answering these questions. Dana