Trunk Center Pan and Mini-Tub

[Mikamaro]

1968 Camaro, on jackstands under rear end. Doing a trunk center pan replacement. Got the old trunk almost completely cut out and cleaned up. the gas tank braces are still in and welded fwd / aft. Trunk is only removed between inner frame rails. Question is should I start my mini-tubs now? Better access than being curled up in the trunk. Do I have to worry about having too much of the car cut up and having the body shift around?

Also, where does everybody support the back half of the car if not on jackstands under the rear end? Can I leave as is or do I have to remove the rear end / leaf springs?

My original plan was to finish up welding the trunk pan then dig into the tubs but seeing the better access w/ the trunk pan missing has me rethinking...

Thanks,
Mike