We have 7 travellers in the group. Can we hire a private van from Guangzhou to Kaiping? Pls advice.

There are several direct long-distance buses at Fangcun Bus Station that can take you to the destination directly. This way is also convenient.
If you still want to hire a private van, you can go to this bus station. There are some vans for you to choose. The fare is CNY 300 to 400.