Hi Christoph,
the customer namespace is just a part of the path. So if you would have a service called /abc/test_service, than the service should be available as /sap/opu/odata/abc/test_service. You can see that also in transaction SICF.
So from the information I have I would assume that it should work. To which controls you bound the data from the model, so that you have seen that there is "no binding"?
Regards,
Florian