Here is the battening in the back cabin. The photos are taken looking sternwards.
Those toward the front of the boat have cut outs to span the stiffening stringers which are installed in the straight panel sections. Where the panel is curved at the stern end of the cabin, the curve in the sheet stops the panel buckling. Therefore the stiffeners are not needed and consequently the battens need no cut outs.
The battens are self tapped into small tags welded on in advance . The battens were also Gorilla glued.
The photo below shows the tags along the edges of the inset panels before the battens were mounted.