Here is a photo of my house bank. It is 4 t105's in a box I built out of 1'2 marine ply and epoxy. I went with four batteries so that if any battery went bad that pair could be removed and I would still have a functioning house bank at 1/2 the capacity.
I use a Odyssey marine start battery mounted on the little shelf above the stuffing box. It is very small for the cranking amps it produces.
All charge current goes to the house bank and the start battery is charged via a Xantrex Echo-charge. I use a Blue Sea 8686 dual battery distribution panel. It allows both banks to be turned on with a single switch and remain isolated. It has a second position for emergency parallel.
PSC 31 journey