I have the Norvel .40 gas and it doesn't require a lighted glow other than to start. I don't know why it works but apparently it does. I only purchased the engine a few months ago and haven't run it. Maybe it's a high compression engine and it's combo of the plug and some diesel action going on or something.
The Tower page only indicates you need a glow starter, but doesn't say onboard glow is necessary.
OK, I just downloaded the manual from Tower and no, onboard glow is not required. It operates just like any other glow engine.