Looking good with new drawing :D
Four unique paths and four unique lengths. Three Cables for Each Length.
1) Cable Length of Battery Positive to Inverter Positive
2) Cable Length of Battery Negative to Inverter Negative
3) Cable Length of Battery Positive to Charger Positive
4) Cable Length of Battery Negative to Charger Negative
1,2,3,4 can each be a different length. but all three cables for each 1,2,3,4 connection need to be the same.
For each connected device (for example, the outback charger) and polarity connection, each wire going to a given battery terminal ought to be the same "length" electrically. The real measured thing is Electrical Resistance, and having equal length of wire of same size and metal with same end connectors is a reliable way of matching this Resistance. With your setup, that means three cables of equal length for each polarity connection and device.
(2 polarities * 2 devices = 4 unique paths) Each unique path needs all cables to be same length. Four unique paths, three cables per path.
Outback charger would have 6 six total cables. 3 for positive, 3 for negative. All 3 positive need to match in length. All 3 negative need to match in length. But the matched positive length and matched negative length can be different.
Hope this helps! Seems like you already got it, looking forward to future updates. Cheers!