i have seen many cage pics lately with a "box" that supports the hoop, etc. this looks like a good way to get better access to weld the bottom of the hoop, front tube down by the A piller, etc.

not sure what part of the rules allows this. if it is the reinforcing plate then does the box count as part of the area? and for those that do this, is there anything "in the box" to prevent it from being "crush-able"?

correct section right?

9.4. ROLL CAGES FOR GT AND PRODUCTION BASED CARS

3. Mounting Plates
a. Mounting plates welded to the structure of the car shall not be less than .080 inches thick nor more than 0.25 inches thick. The maximum area of each mounting plate in
the Improved Touring, Showroom Stock, Spec Miata, and Touring classes shall be 144 square inches. Plates may be on multiple planes but shall not be greater than 15 inches on any side.