So I have the finished shots of the rear storage shelf.
Finished it with carpet, and tie downs which are countersunk into the ply.
The over-top latches secure the shelf and when undone, allow the hinge to open the shelf up for easier access and to store items which are taller than the shelf space.
I'm really happy at how it all turned out.
You can't get access to the under the shelf with the roof off, so it is secure..