Strange Apparitions stands up on its own, however.
That's why I suggested that the unrelated stories would fit better in a separate volume.
In a perfect world I'd like to see the following separate volumes:
- Miscellaneous Rogers Batman work (Calculator, DC Special, the Secret Origins GA Batman story, maybe even the Clayface arc);
Strange Apparitions, ending with the Laughing Fish;
Siege
Dark Detective
In the end, you'd have three different Rogers "novels" plus a short story collection.