Great stuff. Thought it would be that cable somewhere. Keep an updated diagram as you learn what is what then if you have any issues in the future or want to upgrade anything you don’t have to re-learn everything again.
Solar isolator looks good.
For the pos side of stuff from the LB the order is:
1. LB post
2. Short cable to main LB fuse - 100A should be fine as battery can only put out 100A max. It must be less than cable is capable of though.
3. Cable to isolator (can be any length to help with positioning). Same cross-section cable as above.
4. Isolator. This will be M10 posts.
5. Cable from isolator to busbar (same cable as 2 and 3 above).
6. Busbar.
7. Individual existing cables with new crimped connections attached to busbar. from busbar. Each must be fused very close to busbar to protect cable.
You could use the existing fuses or use something like the
mega/midi fuse box I linked earlier from 12voltplanet which is busbar and fuses in one.