You fuse for the wire gauge, but you have low amps for the gauge, so be interested in what others say is proper.
My old Vector manual says to fuse and wire for the surge capacity of the inverter. Their 3000 surge 6000 spec is a 500a ANL with 2/0 to 6 ft and 250mcm to 10 ft
Balancing an odd number of batteries is with all those linking wires fanned out as in that smartgauge article. I like to bunch them into big 12s and parallel the big 12s and load the monster 12.
IE, parallel two, parallel three, and parallel the two bunches