Using a switch at the brake light will only work if you switch-over the electrical load, e.g. switching from the LEDs to a resistor (2W, 270 Ohm -> 0.5W Load DC). If you just open the electrical circuit, you'll get warnings on your dash (brake light dead, if engine is running, engine light turns on).
Alternatively use a breaker switch on the rear and front brake switches to disable the input to the ECU.