[Wavery]

I would suggest a couple changes in your basic layout.

#1. I would put the 2 batteries side by side and attach them in parallel with either solid copper busbars or very short (maybe 3" long) 1/0 identical length cables.

#2 I would run a 6" - 12" long (maximum) 1/0 cable from one positive battery stud to your positive distribution block.

#3 Attach your shunt directly to the negative stud of the other battery.

#4 Run the exact same length cable from the shunt to your negative distribution block. (equal cable lengths are very important).

Now you can run your positive and negative (appropriate sized) cables to your devises from the distribution blocks.

#4. Place your inverter 6"-12" (or as close as possible) to your positive and negative distribution blocks. Run as short a 1/0 cable as possible from your positive distribution block to your 150-175A ANL or Mega fuse block. Attach the other side of the fuse block directly to the positive side of your inverter if possible. If it's not possible to to attach it directly, use a heavy copper busbar or a very short 1/0 cable.

The objective of all of this is to shorten your cables as much as possible from the batteries to your distribution block and on to your inverter. The longer the cable, the more resistance. The more the resistance, the less the efficiency and the higher the heat. Heat is waisted watts.

Moving on to your solar. I've never seen a solar isolator before but I would think that it would have a built in circuit breaker of some sort. I'm not sure what that is for. The thing about the solar cables is that they need to be fused (or isolated) in both directions. The idea is to protect the cables from a short. If you put a fuse on the positive cable, you should also fuse the negative cable. I personally used a double 40A DC circuit breaker.

When making custom length cables, it's important to use the proper size pure copper lugs and a proper crimping tool. Most of the pros use hydraulic crimpers. I couldn't see the investment for a one time project so I (and many others) used the $15 "Mofeez Hammer Lug Crimper Tool" and it worked great.

EDIT..... I just notice that your distribution blocks are 1/0 gauge in and a max of 2 gauge wire out. You might be able to get away with 2G wires from the distribution blocks to the 2000W inverter but it would be best if you doubled up. That is, use 2 of the distribution block terminals and double up the wires on the inverter, Experiment by running your microwave for 5-minutes and check for heat at the inverter terminals. It should be fine.