Duster reverse dash light wire routing.

Unfortunately, I don't understand what these pictures represent.
Yes, with the manual transmission, there a wire from the clutch pedal to the starter relay. But it's distinct from the transmission reverse light switch and has no connection with it.

The reverse lights wiring is simple.
Do you have a black wire entering into the "Z" terminal of your bulkhead connector engine side?
If yes, this positive wire comes from the transmission switch and goes to the reverse lights thru the bulkhead conn.
Inside, if you have a 4-speed transmission, the white wire is divided in two : one wire goes to the rear of the car, and the other goes to the dashboard reverse light. With the 3-speed trans, there is only one white wire (no dash light)