Retrofit kill switch on 1970 Commando

I am in the process of rebuilding the wiring loom on my 1970 Commando. The ignition switch, however, is placed by the battery and I am dreading if I ever have to kill the engine by reaching down and turning off the ignition at speed.

Do anyone have a suggestion for a kill switch I could retrofit? I have the original Wipac Triconsul fitted and I would like something which is not too intrusive and fits the bike.

Fit a Wipac Tricon on the other side of the handlebar and use that as a kill switch, either as circuit breaker or make to earth to suit your ignition setup eg points or EI.