Thanks Jay.
The rear rack is somewhat of a work in progress.
I didn't like either the look or the sturdiness of the stock rack/back rest system so I set out to do something that fits my own personal vision and practical preferences.
The new rack is very sturdy. Incredibly so. The intention is that it forms the base for three different set ups.
1- as a basic luggage rack. So, for example, if I want to carry a huge, heavy bag/case then I can screw a large base on top of the rack which will support it fully.
2- I have a special aerodynamic hard-shell 'top box' which I sometimes like to use, so the rack can integrate with that solution.
3- The stock pillion seat isn't to my wife's comfort requirements, so I can use the rack as a base for a wider/bigger seat pad, which i'm in the process of designing/making.
Here is a link to when it began and where it's got to, so far:
Designing a new rear fender - winter project