Sounds like you're on the verge of a mini riot.  Get your neighbors together, and run them folks out on a rail before any trouble starts!!!! It's for the children.  

Really, though...so what...If they do something suspicious, well, then go ahead and report it.  Staying up late isn't really that suspicious.  As for the cars and choppers...they're watching you, cuz you have evil guns.  Those nice folks next door don't, so they aren't any trouble at all.

At the VERY LEAST, call immigration, have these rag's visas checked.
Then, to counteract the jackhammer noise, fry pounds and pounds of bacon all day and night with your windows open. Send that lovely fragrance wafting across their tent. Pour the grease outside, all along the property line.

Oh geeze. Chill people.

You said women and kids...so there's obviously something else going on.

Has it occured to anyone, that given the current climate, perhaps most people work at night because that's all the jobs they can get? Or, because of their current jobs, they gotta pull massive hours, and either a) leave really early to get to work or b) come home really late?

Don't pass judgement before you have proof. You never know.

They might be honest to God real American Citizens...perhaps born here, perhaps naturalized. You just don't know.

It can't hurt to go over one day after normal work hours, knock on the door, say hello, and you're here to welcome them to the neighborhood. Be friendly and all....they may very well turn out to be nice people. The skin color does not determine anything, as we all well know. Same with religion. (Need I point out McVeigh?) You might get an answer at the door, you might not. You might run into some irate guy who's seriously pissed you woke him up; you might run into a guy who's studying like you...so on, so forth.

All I'm sayin, is that it's better to approach from the front and find out in this case...than it is to sit there, stew, and never really know for a fact.

This is, after all, America...not the Soviet Union.

My $0.02, take it at face value and no more...

Ed