I think the short answer is you can’t do it easily which is why Phil mentioned a sub panel. Your power converter is powered at your distribution panel so if you power the panel by your inverter, you are going to power the converter.
Since the both cables run from the batteries to the Inverter, why would they not be the same length?
Steve and Andra
2012 F350 6.2 gasser SRW LB
Fab Fours front and rear in case we run into a rhino
2019 Northstar Laredo SC