Step 9:

Picture of
Contrast on this image is tuned up to help see detail.  After some consideration I re-opened the wall in the closet, disconnected from the vent stack and redirected the pipe for a dedicated vent stack of it's own.  Typically a bathroom fan uses a four inch pipe but the volume of air being moved is small and the fan is very small so it won't be stressed.  Larger fans require larger vents or you'll stress the fan.  (Imagine a vacuum when you suck up a sock)