Proof of onward Ticket if using Boat/Ferry

Hi,
We plan to use : 144- H- Visa Free, From Australia transit China to Taiwan( Australia --> China ---> Taiwan).
If we use Jin Men (Taiwan) as our destination out of China, and we are going to buy Ferry/Boat Ticket from Wu Tong Ma Dou , Can we use confirmation letter from Boat/Ferry company that we have purchased the ticket as a proof of onward travel from China to Taiwan ? Do we have to provide proof that we have a VISA for entering Taiwan ? Accommodation at Taiwan as well or China ?

Thanks