As I mentioned earlier, this behavior is by design and the changes will affect the control in other scenarios. We will consider, however, improving the control's behavior in the feature. For the time being I recommend you use the RadRotator
control in RotatorType="FromCode"
and implement custom rotation.
For your convenience I've attached a sample to this thread. Please, note that in the provided code I have used an additional variable - viewportItemsCount.
You need to set this variable to the count of the simultaneously displayed items.
I hope this helps.
the Telerik team