If you plan on an inverter I would go with 2/0. When it comes to the DC loads, bigger is better (to a point).
Welding cable works great as it has many fine strands of wire, makes for a flexible cable. Important when you start bending this stuff around in tight spaces.
Marine battery cable works great too, but it is "tinned" (copper strands are coated for moisture protection). That makes it pricey.
Here are two sources for comparsion:
http://www.mcmaster.com/#welding-cable/=awxyha
http://www.westmarine.com/webapp/wc...toreNum=10109&subdeptNum=10605&classNum=10606
Both sources have cable ends.
West Marine also has an excellent selection of thermal breakers and heavy duty fuses.
With the cables I have running to the rear of my truck, I have a fuse like this mounted up in the engine compartment.
http://www.westmarine.com/webapp/wc...toreNum=10109&subdeptNum=10598&classNum=11287
If you have a local welding shop close by, that may be your best bet. Work a deal with the counter guy. Buy the wire you need, make you runs and cut the wire. Bring it back to have them crimp the connectors on. Unless of course you have your own crimper.
When you get home get the hair dryer out and add some adhesive lined shrink tubing.
http://www.westmarine.com/webapp/wc...toreNum=10109&subdeptNum=10611&classNum=10612
http://www.mcmaster.com/#heat-shrink-tubing/=awye12
Odds are, once you add an inverter, batteries and the box. the proper cabling, connectors and the ancillary stuff to go with it may be 20% or better then your battery and inverter costs.