Interesting concept. Do you realise the Mopar's are unibody and the "body" is all part of the floor which is the chassis. It would be a monumental task to make it happen.
I was thinking about that. Haven’t figured out a way around that yet. I was thinking perhaps to run some boxed steel tubing along the floor to stiffen the chassis side-to-side at the a, b, and c pillars while the floor is cut out and everything removed, lower onto the Tesla “frame” (battery packs connected to motor and suspension). Connect that and fabricate new floor pans.
Looking at a cutaway of the frame I’m not sure where 2 inches could be saved. I think there may be a crossmember about halfway through the battery pack to add rigidity, which could be removed and crossmembers could be relocated underneath to keep structure for the battery pack.