You can use the navpoint / route system that is in the survival game sample:
But there you have to place the routepoints manually.
If you want to go for a more realistic automated route, i would suggest to keep a minimum distance to the borders of the navmesh, like 1 meter for example.
As a human you would go the original red line from A to B with some distance to the walls.
If you want more of a robot/drone behaviour that really goes in the middle of the paths, then i would set up manually a mesh of navpoints, its quick to do.