Today I fitted a buzzer for the indicators. This was off ebay & is diode protected. It was designed for a motorbike with two power leads (left & right) and an earth.
I chose to make connecting leads using connectors & a Y lead to the existing leads under the spare wheel so the loom isn't cut.
The leads then pass via a small drilled hole is the saddle board to leave the buzzer under the side of the drivers seat. I sealed the hole with white bath sealant.
Not so difficult and now I can hear if the indicators are on.