Outrigger design sorted, next up was the crane proper. It's much like the outriggers, telescopes, but has three actuators rather than two and lightening holes.
There's actually about ten feet of synthetic cable (err, nylon string) on each winch.
The base of it is this thing
I think eight pieces glued together. Primary and auxiliary winch servos go on the left, hinge for the crane on the right (when assembled, has brass bushings for the crane to ride on), and bolts down to the crane rotation mechanism via the four holes in the base. The big center one is clearance for the rotation mechanism, which is 608 skateboard bearings and an M8 bolt down through the crane transom.
The rotation mechanism is a big honking gear as base, driven by a tiny gear on a low-profile winch servo. Said big honking gear rides on more 608 bearings.
The orange thing is a rounded cover so the wiring harness doesn't snag.