Battery placement and question

[Awarsoca]

i have a 94 Hewes Bonefisher with a Yamaha 90 2 stroke
I run the boat once or twice a month
Lights, bilge, Garmin D73v NO trolling motor. I want to add a Bluetooth amp in the center console to run some speakers at some point.
When I bought the boat in May I was told the owner prior to my seller had a trolling motor mounted off the stern on the poling platform. The Boat has 1 battery with everything wired to it. There are some battery cables running from the center console to the rear and currently not connected to anything. 
I am trying to figure out the best way to install two batteries. I will add a Perko in the mix. 
Adding the battery to the CC , as best I can figure, it would only be connected to the Perko as all the wires are already by the original battery. The amp could be wired to that in the future. Does it even make sense to add the 2nd battery, other things than straight up piece of mind when I'm back in the creeks?

 

 

[Fishtails]

I think a BlueSeas switch would be a better choice. I have two batteries for trolling motor(24v) under my console and my cranking battery is in the starboard stern compartment. 

Hope this is helpful.

p.s. There is a lot of info on the "favorites" section.

[polliwog]

My 2 trolling motor batteries are direct to the trolling motor with separate charger .  The third battery is direct to the motor with a separate charger.  Make things simple.   Most of the time the main  engine  battery is fine without charging.

[polliwog]

 Are you going to have a trolling motor? If not bag the extra battery.  Buy a lithium jump battery system and don't worry about running out of juice.  They are terrfic and powerful.  Will start your motor in  a flash if somehow the battery won't start the motor.  $75 and your  good to go. easy/peasey. I never leave home without mine.  They are tiny and weigh nothing.