For each of the image references, if you select the "DATA" tab (Square with triangle and dot) in the Properties panel, check the box for "Opacity" and change it to "0.5", it will make the reference images slightly transparent. I made the box wireframe and then lined all the views up together in top view, then front view and then in side view, I selected only "Right" and "Left" images to move along the Y-Axis to line those two up.
