I think that some one already suggested this already, but here is the link to the blue sea systems ACR kit. It is rated at 120 amps and it can parallel the battery's if needed to emergency start the motor.
This way you can just have a battery for starting and the other to run your electronics.
http://bluesea.com/category/78/79/pr...e/overview/329
Or if you have a larger battery banks you can use this system:
http://bluesea.com/category/78/79/productline/388