Before that, over the weekend, I might get the "holes" at rear resolved over the weekend, if all works out OK. Once that's dealt with and the new plywood floor above the wheel wells is installed, the rest of the old floor is coming out. That also involves removing a number of large, rusty nuts and bolts, which complicates things. I'm sure I can remove the old plywood floor without too much difficulty, but the nuts and bolts need to be out of way before new plywood floor can be slid into position.
We'll see how it all goes soon enough. I'm impatient to be making progress but the bright side to the next few lukewarm days is that it should give me time to double check everything, dry fit all the components, and generally make sure that once the weather cooperates, things will go as smoothly as possible.