A proper wire-harness visualizer would run in place of pcbnew in Kicad. A harness still has a schematic (albeit usually without components in it), and then the

A proper wire-harness visualizer would run in place of pcbnew in Kicad. A harness still has a schematic (albeit usually without components in it), and then the physical instantiation of that schematic has properties like trace width, er, wire gauge and stuff. It has an orderable BoM just like a board. If you decide that a particular pinning would be easier, you should be able to back-propagate the changes from the harness up to the schematic. All these things already exist in Kicad. This would allow some sheets of a Kicad schematic to be the boards/modules, and some sheets to be the harness that connects them, and only the physical boards/harnesses would differ. (I've used both WireViz and RapidHarness and while the latter sucks less, they both suck. Being completely outside my existing EDA worklfow is not a feature.)