Battery cable and fuses

I am am putting together a NG lithium bank of 4-200 AH Batteries. I was planning to use the LYNX Distribution and LYNX BMS. How do I determine the cable and fuse side from the batteries to the LYNX Distributor and from the BMS to load bus. Is there a percentage of the possible load I should use size to largest single load. I don’t need to scrimp on cost or performance just the ability to fit larger cable in the battery locker.

Local regulations play a part but this is some general info.

I have made some specs up here to make life easy.

What is the max from the battery if this is eg 200A just work with this but i would recommend sizing this way all dc loads by adding up recommended fused for them as a 3000va multiplus at 48v uses around 60 amp but needs a 125 amp fuse for peak use. so in this case dc load would be 125 amp and i would go up a fuse size to 150 amp. Add up charging using a similar method 40 amps for a 30 amp charger based of the reccomended fuse size and lets say 30 amp multiplus charging but ill go up a fuse size although it has the 125 amp fuse That would be 80 amp charging so the battery cable and battery has to handle whatever one is larger as the inverter cancels out charging current ect. You can add them and that is better but you need it the smallest. and go up one cable size from what is needed.
I do not mean going up an actual fuse size but it is a nice margin of saftey in the calculations i can work out from your specs

I hope this makes any sense