I also used the Blue Sea battery switch but I used the one for
a single battery as I did not want to run extra battery leads
back to the power center area.
I mounted the switch in the toe kick area under the cabinet right
next to my power center.
It was an easy mod and took only one beer to complete!
While I was in that area with the cabinet opened up I
also added another 15 amp circuit breaker to the 120v side
and stuck another duplex receptacle next to the battery
switch. Now we can perk coffee AND have our electric heater
on at the same time without tripping a breaker.