First scale and align the views in photoshop so they match each other. Use the guides and your eyes to make drawings match.
Next, clear guides and draw only two new guides like in image below:
With rectangular marqee select areas defined by guides and image borders and copy each one into separate file. That's it.
Note that back drawing should be positioned inside coresponding image in a same way the front view is - so back is just positioned and matched to front image.
