I have learned a lot with my solar install and adding the extra batteries. My latest reality check was the
positive battery post terminal fuse. The battery bolt goes through the hole on the left and the wire lug on the top above the fuse. There is a cone shaped insulator that is not shown well. It is under the nut. A great $30 insurance policy. Since I am now running an inverter I went with the 300 amp fuse. They recommend a minimum of 50% above your calculated battery draw.
I remember hearing about a few Montana's having fires because 12 volt cables chaffed going through the frame. The terminal fuse would be a great safety feature to prevent that. I have them on my batteries now. If you intend to install one I suggest a single wire from the battery bank to a connection post or buss strip so a single terminal is connected on the terminal fuse.