Kiwi,
Not sure to be honest, it's a sterndrive version remember, so has the engine bearers and associated stuff, and is Balsa core 'all over', has all the structures in for the cabin, and cockpit seating, so no that light.
I would take a guess that the bare boat weight was around 1000 kilos, certainly approaching that anyway. all-up weight with interior, tanks, batteries, pig iron (engines) drives etc, etc,etc, is a tad over 3000 kilos.
can you get a pic of a 'Steadecraft Shadow' and post it, would be very interested to see it!