I've had good luck in all my teknos putting it on the tray in between those verticle groves on the tray right between the motor and ESC. That combined with using Velcro to keep the body on prevents anything from getting up in there, just have to make sure your wires don't flop around and get caught on it.

If your really paranoid you can do the same thing, but mount the switch low enough so the top of the switch is flush with the tray vs. the base so you would really have to reach in there to flip it.

All that said, I would really like to see some innovations to make swapping out the battery faster, which would have the side effect of not needing a switch for a fast turn on. I really enjoy running the 20min mains with the nitros, i'm pretty good at strategy and driving patiently so I do better in the longer races vs. just being full throttle - full break without concern of running out of battery / fuel.