Ukraine

Yup, I'm aware of those. Not a new concept: https://en.wikipedia.org/wiki/Airborne_aircraft_carrier And you're right, that sort of research effort has to happen rather than be diverted purely to operations. So if they can make it happen, and the weather cooperates, GREAT, meanwhile hitting those last two sites is still probably not worth too much extra effort vs revisiting other targets. But it costs nothing to check the weather in the meantime ;-)

ETA: but don't forget those drones are not going to be wire guided, so unless they also have automated targeting and non-GPS location services, they are going to get jammed to hell. Also, launching one might "fly under the radar" so to speak, but one isn't going to do it. So then you have to have a swarm. And you know what a swarm of high altitude ballons does? Stand out on radar and move slow. Making it very easy for a defender to mount a defense.