Kingman's interesting for this sort of thing given its proximity to the old crash site. Not surprised at all. They do love a night convoy don't they - less witnesses, less chance of some bloke with a smartphone getting too close.
What were the vehicles like? Flatbeds with covered loads or more of the armoured personnel carrier type? Because those are two very different conversations. I've seen similar stuff roll through parts of Lincolnshire near RAF bases and the covered flatbed ones are always the ones worth paying attention to. Could be nothing, could be something enormous under those tarps.
Anyone manage to clock which direction they were headed after Kingman? That'd narrow things down a fair bit. If they're going northwest that's one thing but southeast toward the testing ranges is a whole different story.