How do small unmanned fixed wing aircraft protect themselves against lightning strikes?
You design your structure, as in larger aircraft, considering where the strike could potentially hit first, and where it would leave.

The rest is electrically bonding everything together, and creating a continuous electrical route from each entry point throughout the structure to the potential exit zones.

Calculating or measuring the electrical resistance throughout the paths is the way to quantify the effectiveness of the design. If it’s zero, the lightning would not hit this aircraft (or would pass through it without causing any harm). However, this conflicts with the scenario of triggering lightning strikes. 

To attract lightning, you can simply put a sharp, massive metallic pole, in electrically isolated from the rest of the fuselage.