The parts that are hidden by the Piccolo are visible in the mockup photo. It’s just the key part from a Piccolo rack that’s been cut out.
The one detail that’s not visible here is that Kurt beefed up the welds between the cross-bar from the rack and the sidebars. As you can see in the mockup photo, they were just lightly tacked together in the original frame.
A nice feature of this over the Xtracycle Mods I’ve seen and done is that here the interface is recessed just a bit, so the top of the rack remains flat, and can be used for other purposes. (Such as being covered again with a cushion to be used for a seat). You woudn’t want to sit on the Xtracycle version of the mount!
This solution is super-solid, without adding much weigh to the frame, and there are no nuts and bolts in the frame to loosen over time.
We stress-tested it some, applying torque to the Piccolo from different directions, and the frame portion doesn’t budge.