Thanks for the replies and pictures, very helpful.
On the CS companion CD, there are some pics of a CS with forward floorboards that can also be placed at seat top level, one on each side between the seat and centerboard case. This creates one large flat area rowing thwart forward.
I imagine this was to create a large berth area on the CS, but when I saw the pics I immediately saw double duty as an area for the dog while underway (yes she goes along anywhere dogs are allowed, 65lb lab/retriever mix that just LOVES the water).
Based on Howard's pics, creating a forward flat area should be possible on the Spindrifts as well. The vang might get in the way, have to explore further.