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The hook ups have been modified. In a two battery hook up there should be only one cable per battery post, except for, the negative post of one battery which goes to the chassis ground, and the positive post of the other battery which goes to the "house terminal post". All positive connections(generator, solar, chargers...) should be made to the house terminal post. Your house terminal post is shown in your first picture in the upper left hand corner.
For peace of mind, I always add a catastrophic fuse in the connection of the batteries to the house terminal post. This is a requirement in boating and from my perspective should also apply in RV's. If you are going to add a battery monitor then it would be placed in the negative connection from batteries to chassis ground. I added a third battery under my steps and found a battery watering system makes maintenance far easier.
Hope this helps.
2018 Four Winds 31Y