inductance - WPC Inductive Power Transfer

I am building an Inductive Power Transfer (IPT) system. As of now I am using a design based on a flyback converter. It works great but I am having issues adding features such as power control feedback from the receiver coil and load detection.

I see this has all be solved using the WPC standard as shown below.

The issues is that these WPC standard IPT systems are only 5W. My flyback design is 20W. Can anyone help me accomplish this for a 20W system?

Thanks!