ALTERNATE IDEA: I know it’s a little more complicated!
I designed and installed a similar mod which adds a commonly-used trailer towing diode to safely merge the LO and the HI BEAM wires. It also keeps the Front Marker Lamp working normally when the ignition key is in PARK. The diode is rated at 6A and the combined current for both LO/HI lamps is 4.5A so there’s plenty of current margin.
The diode can be purchased online or at any RV Trailer dealer.
Blue Ox
BX8864, 6 Amp Diode Single Pack, $15.50
http://www.blueox.com/towing-accessories/bx8864/
My schematic changes are shown in the picture.
This mod is installed behind the windshield fairing.
Using a Quick Splice T-Tap Connector (14-18AWG), splice onto the WHITE wire between the 39B Connector and the 38B Connector. Using a short piece of 14-18AWG wire, connect a Quick Splice Female Connector terminal on each end. Push one female terminal on the T-Tap Connector and push the other female terminal onto the Blue Ox diode male terminal (pick one of the blue ox male terminals on the end where there are 2).
Cut YELLOW wire between the 24A Connector the 38B Connector. Install a Quick Splice Female Connector terminal (14-18AWG) on each end of the cut yellow wire. Push the female terminal which is connected to the 24A Connector onto the other unused Blue Ox male terminal on the end where there are 2. Push the remain terminal which is connected to the 38B Connector onto the Blue Ox male terminal on the end where there is only 1.
It's a pretty easy mod but proceed at your own risk - anytime you modify a bike there's always a chance of messing up.