It sounds like you're trying to test a "Crane Operator Simulator" game, a la Half-Life 2's crane section. In this case, it looks like you're trying to have a bridge-style shipping yard crane instead of the standard boom-and-arm style crane.
I've been a Unity developer for the past 3 years, and I've developed a number of physics-based games, some with complicated rope physics. This seems relatively straightforward; I think there's three major components:
- the crane on rails, but still physics-based
- rope physics - I recommend the Ultimate Rope Editor asset
- extend/retract hook
- hook automatically attach, detach button
Shouldn't be any issue with putting this together in about 8 hours. Please let me know if I can provide any other info. Thanks!