The "wall" behind the seats in the Coupe takes up a lot of room. What is underneath it? Can it be removed or modified to provide more rear compartment space?

Here's what's behind this question: I'd like to take a cross country trip but would really like to pack a full size spare tire. Obviously, I need two things - 4 wheels/tires the same size and more storage space. I've seen threads where some of you have made the wheel/tire switch-what are the pros and cons of this switch?

HELP!