JW,
Your assistant does not need to know how to fly. Have them hand launch with the wind at their back, the plane slightly up and pointing straight ahead or slightly to the outside of the circle. Make sure when they release it they let go without putting any kind of spin on the model. From your side, keep steady tension the lines, the controls at neutral, and step back as they launch to maintain line tension.
If you take off from ground, you might use a long piece of cardboard to launch from. Have them release straight ahead and not push the plane. Again, keep tension on the lines with slight up elevator and step back as it gets airborne to maintain line tension.

RW,
If the wind is blowing from the west, you want to take off from the north so the wind will assist you with line tension as the plane gains speed.

Good luck guys. Keep us posted.

George