Zero gauge is a bit overkill, 4 or 6 gauge would likely do the trick. What are you planning on running off the inverter? With the cost of an additional battery/isolater/wire/fuses/etc., would your money be better spent on a small lightweight gas/propane generator? Depending on what your needs are, you might consider a portable power station they can be charged from 110, 12vlt, or solar panel
With the size of your alternator, you shouldn't need dual batteries, it will generate more than enough amps to run extra lights and a winch a winch, the battery's only real purpose is to provide the amps/volts needed to start the engine, once running, everything should draw its power from the alternator.
