Looking very nice - are those the back classic/20l ortliebs that you've managed to fit to that pizza rack? Any problems with the hook getting knocked off at all?
Yes it is, and I did, so I semi fixed it by flipping the rail over so from this:
to this:
It means the rail sits further down from the tip of the hook. If that turns out to be not secure enough I'll get a second hook like the Gravel panniers use: