How about this?
1. Load Screenset1.
2. Double-click one of MIDI clips.
3. Right-click on the PRV tab and click Undock.
4. Maximize the floated PRV window manually, without using the Maximize button in the upper right corner of the PRV window.
5. Close the PRV window by clicking the [x] button in the uppper right corner.
6. Unlock and re-lock the current screenset.
7. When you want to work in the full PRV with the current track displayed, just double-click the MIDI clip you want to edit. If you want to go back to the original Screenset1, just close the PRV window (1 click) or assign a keyboard shortcut to Revert Current Screenset and hit the key (1 press).