Best sequence for rear end rebuild works

I have had to bite the bullet and admit that the whole of the boot floor and seat swab section will need to be cut out of my Elf and replaced, along with a number of otther panels in the same area. The previous repairs along with the repairs that need doing now would result in the patches all merging into one.

The full list of items to be replaced is
1. Boot floor section, whole.
2. Elf/Hornet Boot Extension
3. LHS Wheel Arch
4. RHS Wheel Arch
5. Rear valance
6. The boot slam panel (not sure what this section is actually called)
7. Rear subframe mounting panel (or heel board to some people)
So my question is what is the best sequence to do all of these in so that the dims all end up as close as possible to what they are now and retain as many reference points as possible during the work. I have taken many many reference measures so far, I'd be greatful for advice on which are crucial.

My initial thoughts on sequence were
1. Remove rear valance & check all the boot extension strengthening bits for re-use. (Doing this early so I can order new ones if needed)
2. Wheel Arch - Not welding to the boot floor.
3. Wheel Arch - Not welding to the boot floor. (Doing these seperately for ease of measurement)
4. Cut out boot floor
5. Cut out subframe mounting panel
6. Replace mounting panel
7. Replace boot floor & extension piece
8. Replace rear valance
9. Replace slam panel.

Would welcome everyone's thoughts.

Just thinking about this... I've not done it on an Elf, and in fact I haven't done the whole boot floor on any of my cars. But last summer I did the arches and whole passenger floor on an estate - I did the heelboard ends rather than the whole thing as it's both pricey and awkward on an estate.

Anyway my thought is that I would do the arches after the boot floor. I had to do the boot floor sides (you can't get a whole floor for an estate), so I used the arches for alignment, then cut the arches out and replaced them. As they were pattern arches they were a nightmare to align, and I don't think I'd like to make the boot floor fit to them - bad enough making them fit to the boot floor. (I also went on to fit new outside quarters to the new arches). My resto pics

Of course we did strip the car to a shell, braced it well, then rolled it onto its side. That made the work a heck of a lot easier. A spot welder is also really good for doing the arches especially.

Cheers for the response. Since posting I have also decided that the arches should be done after the floor, so i'm pleased someone else agrees. My boot floor is genuine, the heel board is M-machine and the arches are Magnum (just the way things worked out) so I've got my work cut out making them fit I'm sure.

You'll need plenty of clamps. 6 pairs of assorted mole grips is barely enough!