I used a toggle switch with a waterproof boot to control the headlight.
I originally spliced the switch into the common ground wire for both the high and low beam circuit. This disables both beams when the switch is on, PLUS has the added benefit(?) of providing a warning that the headlight is off, because the high beam indicator stays on. However, the little blue light is hard to see in the daytime.
I now have the switch spliced into the low-beam feed wire, meaning the high beam is still available when the toggle switch is activated. The beam indicator works normally in this configuration.
Cheers, Miles