AN bolts are commonly available in cadmium-plated nickel steel, corrosion resistant steel (not marine grade) and aluminium alloy, which you wouldn't use. They all will corrode. The cad plated steel screws are the most common and corrode the quickest, you may get away with it in fresh water for a while, seems like you would be downgrading your Tiger by fitting them though.

You could tape the tail of the lockwire or heatshrink it which would be neater.

Maybe you should look into a threadlocking compound, they really are very good.