How to mount ceramic cystern on drywall

[jgplarnold]

What is the best and most secure method to mount a ceramic cistern on a drywall. The wall cladding is called VILLABOARD which is an Australian product and is 6mm thick and the material is hard not like plaster board. The manufacturer states that 8 gauge self tapping screws can hold up to 5kg per screw.
A typical ceramic cistern has only 2 holes for attaching to a wall. 2 screws would not hold the weight of a ceramic cistern plus water.
There is no timber frame behind where the cistern needs to go.
What would the professionals do?

 

[TomFOhio]

Have someone open the wall and with your dementions have them put a backing board in and then re drywall. If you hang it on drywall it will never hold.

 

[Mr_David]

You need to put solid wood in wall that is securely attached to studs.
The anchors have to hold not only the weight of the sink but also the weight of someone leaning on the sink. If the sink is sitting on a pedestal then some times you can get away with using toggle bolts on a hollow wall