So as one of the "drone hobbyists" regularly accused of causing aerial mayhem around the world, I took an interest in what was going on over NJ last year.
Surprisingly I was unable to ever find even one frame of a video that proves these were even drones. Witnesses which included local police alleged there were car-sized drones flying at low altitudes all over the state and coming in from the ocean.
The dimensions and flight times didn't align with any hobby drones I know of but I finally found a culprit and a guess at who was operating them.
This hybrid drone uses 4 electric motors for VTOL and a gas powered combustion engine for horizontal flight. It has a flight time of 12 hours and has a roughly 8 foot wingspan.
What they were most likely doing was LiDAR scans in preparation for a future construction project. My guess is it was the Army Corps of Engineers or DOT who got permission from the FAA at night and chose this time of year because of the longer night cycles.