how's that? i've got 2 runs of 1/0 gauge from my front battery to rear, one for positive and one for negative. battery to chassis in both front and back, battery to alt in front. you're lucky you get to run a lot less than everyone else.
all you have to do is run one wire from your battery in the back up front to your alternator, and fuse that one for sure since it's running all the way through your car. ground the battery to chassis in the trunk, and your alternator to chassis up front. call it a day.