My comment: Flying at night, up to 40km away, is technically difficult. But smart autopilots, using GPS and accelerometers, mean that the operators (pilots) don’t have to do hands-on flying except landing and takeoff. Probably every component in the system except the ground vehicles is hobbyist level, although some of the specialized long-range radio gear might need to be hand built. Nothing from aerospace companies. Battery powered, so essentially noiseless. Also, the aircraft itself is the cheapest part of the system.
The article mentions flights of “up to 4 hours.” That is a very long duration, and would require lots of batteries. 2 hours or even less sounds more realistic. Efficient cruising speed is probably is probably around 40 kph (25 mph). If anyone finds other discussions of this project, please let me know.