For the side wing they still need to cut from front (chin) to back (posterior jaw angle) along the mandibular border. So, the prior BSSO cut very well could preclude the side wing. But you could always check with doctor to make sure.
Technically speaking, the side wing doesn't really elongate the ramus. But ya, it can give that appearance by prying downward (dropping down), at the mandibular border, the posterior jaw angle as to decrease its angle of inclination of the jaw line.
Have you considered just getting a posterior angle 'drop down' implant for the changes to the jaw line contour you seek?