The lines of the backbone will give the rigid frame appearance the owner is after.
Using some 6mm clip-nuts on the seat brackets to hold the rear hump down. They are self-centering and hold in place nicely till they can be welded on the inside, and then the rest of the bracket can be ground off. Also nice not having to strip zinc plating off prior to welding. The cross-piece will be used to mount the electronics tray.
Some anodized grommets dress up the rear hold-down screws.
The cross brace profile was kept low to keep the rear triangle open. For strength , the attachment points were kept low on the tubes and close to the swingarm and motor mounts. The owner wants to try and fit a Cognito Moto oil bag in the front of the triangle. It is placed so that the air filters are shielded from rear tire spray.
Still a long way to go, but the lines of the bike are starting to take shape.
With the rear shock pre-load dialed up to the max, it makes for a perky tail. A 4 into 1 exhaust system is coming next, and will help fill the rear of the bike silhouette.
All welded up, the shock mounting plates run through the box and are welded internally to make a complete box.
With no roadmap to make this monoshock conversion, it was meant to be over-engineered strength-wise while still leaving room for the shock reservoir.