Unfortunatelly this will not be possible.
The issue is that the DF don't have enough information to serialize the results back
to the client for non-scalar query results.
It will try to send a List<ICustomer> back to the client, and the
serializer doesn't know what a List<ICustomer> is.
So the list
form of the query will always fail, for any entity type.
Can you elaborate on why you are trying this approach, so I can better understand and assist?