Hi Patrick,
I am copying the answer from your support thread so it will be available for the community.
This could be achieved by using implicit styles without creating a custom class derived from RadDocumentPane. You will just need to create an implicit style that sets ContentTemplate and HeaderTemplate and set the RadPane's Content and Header properties to their DataContexts when creating them. I prepared a sample example that demonstrates how this can be achieved.
Greetings,
Ivo
the Telerik team