On board glow drivers that switch on only at low throttle have been used for years, LEDZx.

I have commercial drivers that include the Ni-Cad battery, optocoupler driven switch, threshold setting pot, and indicator LED..... and I have built home made devices using RadioShack Ni-Cads and a cam driven microswitch to turn on the glow.

Two clever ideas simplify making on board glow drivers.

Instead of a commercial glow plug clip try using one of the brass adjustable control rod clamps that are commonly used to connect control rods to servo wheels. The kind where you poke the control rod through a hole and turn a screw to clamp the rod in place. Drill out the brass fitting so that it will fit a glow plug, solder a (stranded) wire onto the protruding post and clamp it down on the plug. Simple, reliable, no glitching.

Instead of a fancy cam or complex mechanical arrangement to turn on the switch at low throttle, use a simple RadioShack microswitch (rated 3 amps or more) and a string (maybe fishing line) connected to the throttle (linkage or servo wheel) that pulls the switch on at the appropriate point. Don't fuss with the arrangement, just mount the switch on a little balsa block and when you're ready to make the final setting, slide the block along the mounting surface until the switch just comes on, than put a drop of CA to fix it in place.

The good things about a home made glow driver are the low cost, the extra capacity of a decent C cell Ni-Cad, and the ability to add an extra "failsafe" switch on the outside of the plane to shut the system off so you can fiddle with the engine without getting bitten.