Don't know if this would help as I haven't had time to try it yet, but there was a demo of "Reference Image 1.5" on one of my 3d mag disks (you can download it from the authors website as well. Don't know if it will work with Poser or not, but it creates a window with a very thin frame that can be overlayed part of your working window. When I've attempted to do morphs from photos in the past I've had to switch the display to outline and load the image as the background which is is ok for basic shape but not details. This may help.
the site is 
scary-monsters.org

If you try it let us know how it goes.

Daz Studio 4.8 and 4.9beta, Blender 2.78, Sketchup, Poser Pro 2014 Game Dev SR5 on Windows 8 Pro x64. Poser Display Units are inches