Early 2011, I decided to move my second battery to the front of the truck. This way is more efficient when I use the Winch for long periods of time. There is also less voltage drop when charging the battery since the cables are shorter.
I am using an IBS 200A relay (from Sierra Expeditions) to disconnect the batteries when the truck is off, so I don’t kill my starting battery when I camp for a few days without moving the truck. I have it wired to automatically connect when the truck is running. I also can manually connect them if my starting battery is dead — already had to use this feature.
I installed a second battery in my truck for having extra power when I am camping. All of the accessories on the truck are ran off of the second battery. I have a 4 gauge cable going from the battery in the bed to the front where it junctions to the front battery and accessory fuse block. I can disconnect the batteries with a high capacity breaker, which I am going to replace with a constant duty high capacity relay.