I plan on cutting out the rear trunk floor but decided to weld in some rear bracing first to ensure that nothing moves. I am not really sure if this will drop any weight from the car but it should make it stiffer and easier to work on.

I welded in 1/8" steel plate as a base to weld the 1.5" diameter 1/8" wall tubes to.
I weighed the tubes, plates, and the difference in weight of my welding wire spool and found that the whole structure weighs 14.7 pounds, next I will cut out the floor and hope it weighs more than 14.7 pounds !

I will also tie this rear structure into the main roll cage.