Thanks for the input!
I've tried the light copper wires before but couldn't get enough
current to the plane to make it do much. The wires just ate up
all the power.

You're right about a cut off. You can drain a lipo to where it will
no longer take a full charge. Maybe a third string or light thread
that can be pulled for shut off. A spring could also be used to make
it on/off, so no need for a stooge.