Charlie,
I would personally go down the fabrication route, the shape of the upper plates would be built onto the hull giving you the perfect shape of your hull and a good strong joint, you could use wood or plastic to make these. The vertical section with all the detail could then be added from whatever material you prefer, I think again would use a thick styrene, easily machined or constructed with normal hand tools, drill/filed, this would be followed by the skid, again from bent styrene or even metal section which could be easily pinned to the vertical plate because it has a good cross section thickness.
My skid, the part that runs on the cradle, had a round section where yours has it square which is easier to attach. Moulding one in resin or white metal would be good but you have to make a master anyway.
Regards 17-09 (Alan)