Yes, you can do it that way. They also make onboard glow drivers that run around $50.00 or less that can be programmed to come on at whatever throttle setting you like. If the cost doesn't bother you, that saves working out a mechanical switch arrangement.

You might also try your engine at first without on board glow power. Out of five airplanes I'm running on Gas/Glow, I only needed to put onboard glow power on one, and that was because I'm running a much too large carb on that particular application and the onboard glow allowed me to run a richer than normal low end to get a good transition.

AV8TOR