With a one wire alternator, unless I'm missing something, I think it option 2 is too complicated.

If you like the idea of a relay, put it in the engine compartment and arrange it more like alternative #1.
Advantages would be much shorter path from power source to equipment (ignition, lights, etc).
Alternator to Starter relay stud could be an 8 or 10 gage wire depending on the expected load.

It still should get some fusible links in case there is a short before the breakers and fuse box.
Probably the best location in this arrangement will be at the starter relay.