Here's the wire going thru the interior center console to the back seat. I figured I would put a nice quick disconnect switch here. I used the following wires: 13ft of 2 gauge 13ft of 10 and 8 gauge. I had to get the 8 gauge from NAPAs secret stash in the back. If you can't find in the electrics aisle, just ask. 
Here are the two main grounds I used. One is in the trunk and the other is where the battery tray used to be. A little sandpaper and a couple self-tapping screws will put you in business. 
The screw is right in the middle of the picture. It holds the original batttery ground to the body.

Here's a couple more views. 

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