No!
These cars are unibodies. The floor is a significant part of the structural integrity of the chassis. This should be pretty obvious- in the factory design all that holds the middle of the car together is the roof, the floor and the rockers. While torque boxes and subframe connectors certainly help improve chassis rigidity, they won’t take the place of the floor.
Would it be better than just having a compromised floor? Probably. But if you’re going to take the time to weld in torque boxes and frame connectors you’d be better off starting out by welding up the floor. Patching the floor is no more difficult than adding torque boxes and subframe connectors. If you can add that stuff, fix the floor first.
