According to Cory from Munroe and associates the image shown in Tesla's earning report is displaying a unibody structure. Not exo-skeleton or body-on-frame. I am by no means an expert, but if this is true it seems unnecessary to add all the stainless steel panels...?
Whole point of building it with this shape and materials was because the body was supposed to also be the frame in order to save weight. Should be interesting to see how it competes with the other electric pickups coming out.