In short, a PSU sense line cannot include a diode in series; nor any other active/passive component, for what it matters. Adding a diode as in the schematic you have depicted will prevent the main current blowing up the internal Rsense of the PSU, however, this will also make also impossible for the PSU to correctly measure the remote voltage at the load.
Sense cables can have very small cross-section area (diameter/gauge), as the sensing current will be very small and the voltage drop negligible. This is always assuming that the PSU is being operated correctly. Most remote sensing PSUs does not allow the main cables to be disconnected separately from the sensing cables. This is precisely the type of PSUs the article from EDN refers to,
In any case, delving a little bit more into your root needs, I cannot understand why you want "to sense the voltage drop after the switch". Why would you like to break the power circuit but not the sensing lines? That defeats the purpose of the sensing circuit and it's explicitly forbidden in many designs of sensing capable PSUs.