How to connect "To Workspace" to an internal signal

When you

1. Place the top level of a Simulink model onto a testbench (another Simulink model)
2. Connect stimulus and sinks to the model under test (MUT) at the top level

How do you probe internal signals of the MUT with "To Workspace" from the testbench testbench?

I want to probe internal signals only from the top level of the testbench because

• I do not want the MUT to always dump out saved signals to the workspace once it is placed in a larger system
• I want to use the same MUT version for verification and for its application, without editing

I've searched for answers both inside and outside of Mathworks without success, using several variations of search terms.

My ugly workaroud is to bring signals of interest all the way to the top level as MUT outputs, and stubbing them off with "terminator" blocks. I'm guessing there's a nicer way to do this.

Thank you for your help