Rear closing panel and corner help

[slowmo]

Hi
The previous owner of my bay cut about the rear of the van quite bad to get some mad exhaust in. I'm trying to return it to original but I'm a bit stuck. I'm unsure about the inner arch how this changes to the closing panel and how it's all connected to the outer arch.

Any pics to help clarify would help
Also there is no metal on the chassis member from here back how does the battery tray attach to chassis?

 

[davidoft]

there should be a lip on the schofield panel approx 10mm which is spot welded to the outer arch, the cargo floor has a 10 lip to weld to it, the panel is not complete really but its what everyone makes