It's a splendid idea, and might be workable given the boat's shape.  I should think there'd be some serious engineering work to design the supporting internal structure, and it'd be a tricky business, perhaps not feasible, to retrofit an existing boat.

The Brits love this sort of thing, especially in places with ferocious tides where half the anchorage dries out over the low tide.

.....Michael

It would work. My main concern is that bilge keels create a lot of drag under sail, even if carefully shaped and faired. There'd be a pronounced affect on speed. In light air PocketShip would feel pretty "sticky."

If you sailed in a place that was often windy (like England), the drag might not register as strongly. In that case, the obvious question is: With the existing keel and a pair of bilge keels, why would you need the centerboard? The bilge fins would need to be shaped and sized very carefully to provide enough lift to go without a centerboard. 

At PocketShip scale, the installation of unballasted bilge keels isn't especially harrowing, but definitely not a trivial project. 

To do it right, eliminate the centerline keel entirely and have a pair of ballasted bilge keels...

Wow, alrighty then.  Thanks!