[doaclnr]

Like you said better a dead battery than a dead boat in the middle of the lake... LOL Ive had that happen and its not fun! We will cove out for a few hrs at a time and go bar hopping too. I think your setup will do just fine. If worse comes to worse I can add another deep cycle and run 4 batteries...

[z275st]

Here are a few pics on the setup is on the z275.
Facing the stern, the two starters are on the right and the one house is on the left. The one alternator cable goes to the 3-bank splitter then to each battery. Power cable from 1+2 starters go to battery switch post 1+2. House battery power cable goes to single rotary battery switch under a rear seat. I have the dash clock and radio memory power also on the same power in post that comes from the house battery. Everything else is on the switch off side. A few things such as anchor light and bilge pump go straight to the house battery. The power to the trim pump does come off of a starter also.
I also have a three bank charger connected to each battery that is plugged in any time she is out of the water. My last set of starters lasted seven years and I only retired them out of fear they would die on the water.