Visa Application Info

Hi,
I plan to travel to china from Hanoi (Vietnam) via train in September, unfortunately I can't book the train ticket before I apply for my entry permit due to them not yet being on sale. If I have my accommodation and several train tickets through out China booked including my exit into Mongolia will this be enough to grant me an entry permit?
The entry permit I will be applying for is a Double entry tourist L type as I will be entering and exiting Hong Kong by train also. I am an Australian Citizen if this changes any requirement?
Thanks,
Ben