I only need two boosters right now, but just switched to mifold compact boosters, so they will likely allow the infant car seat to fit very easily on the side or in the middle.
After recommendations from other Tesla owners (my Graco boosters were large and the kids had a hard time buckling) I was still unsure how exactly they worked after reading about them on mifold.com. Took a chance, and the kids love them.
Video review: