I added the 2020 turn signal mountings to my earlier 2018 model.
The plastic section with the fuses under the seat can be removed allowing access to the wiring for the lights.
The 2020 model has connectors coming out of the harness there for the indicators. So this is where I routed the piggyback harness I made to replicate the later model diagram.
There are two side mounted rubber supports for the seat and two smaller screws which hold it down.