Here's my battery intstall.

The battery switch is just in front of the batteries. I tried to keep my cable runs as short as possible, even though I upgraded to 4/0 cable throughout. I didn't have a proper crimp tool, so used a nicopress swager, then soldered each fitting. I'd gotten the optima battery for my toy truck, but ended up getting rid of the truck shortly after purchasing the battery, so got the cheapest possible battery for the truck and kept the optima for a starting battery, then got a marine battery for the house battery. I was going to go with an optima marine battery, but costco raised their prices so I figured the conventional marine battery for $60 was ok vs the $160 optima.

The charging relay and fuses are nestled down under the switch.

Another view showing the ground strap. Just aft of the ground strap is the main fuse on the positive line that runs to the engine.

And here is where you access the power switch at the helm.
I still need to build a cover for the batteries and complete my cabinets. I put together a list of items to finish on the boat, it's suprising long, and not complete! I did manage to add the s/o valve to the fuel system and relocate my transducer last night, so made a little bit of progress.