There is an electronic - solid state - turn signal switch that does exactly what you are looking for that runs on 6V or 12V, LED or incandescent, works both brake and turn signal lights correctly, and is automatic self-cancelling. It's a higher-priced system but well worth the investment because being modern solid state it is literally set-and-forget. All the wiring + the SS module are easily hidden out of sight. I purchased the toggle switch version a few years ago.
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http://www.turnswitch.com/Turnsignal.htm