Deleting folders from Photos Library (El Capitan)

[MotionMan]

If I back up only the "Masters" folder contained in the Photos Library (or clear out everything but Masters from the library), will Photos recreate all the other folders, such as Previews and Thumbnails, and the db's, when I open Photos the next time?

I thinking about doing this in the hope avoiding having to backup an extra ~50GB of data.

MotionMan