Is there a recommended method of maintaining multiple Photos libraries on same hard drive
Honestly Photos.app is not really designed as a pro or semi-pro photo managing application. It certainly seems to handle larger libraries better than iPhoto ever did but if you are taking that many pictures and want to manage them on your Mac you might want to consider an app designed specifically for the workflow and archiving of thousands of pictures.

Adobe has an app for that (Lightroom, I think it is called), and like many Adobe apps is the subject of much praise and anger online. Me, I just use photos.app because my needs are met with photos.app, but it sounds like you might be better served with something more capable than a consumer level photo managing app. IMHO