Minimum I'd do is replace stock, and have 1 in the rear.
I'd recommend the stock to be a deep cycle, and the rear to be a large D31 sized battery.
Personally, I would have deep cycle under the hood, and two in the rear... //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif
nG