Assuming there is no center and no edge to the universe.Also & therefore, it is not expanding from a central point or in any direction. Then the space between the galaxies is just getting larger. If that is true, then the space inside the galaxies is getting larger also.
There are other causes of red shift beyond light sources speeding away. Black holes cause the most extreme red shift.
Quite simply, the oldest light is the most red shifted.
Due to the fact that light in space travels at a constant speed, the only loss in energy could be in frequency or red shifted. There is no way for man to duplicate old or "tired" light except all the oldest light observed is red shifted. To my mind, say a cosmic yard stick is just "getting longer" is kin to belief in religion based purely on faith.