John, maybe I missed something, but why don't you want to do it the night before the party? A long rest is good, and it's always best when fresh. That's why I've got a wsm and not some stickburner that keeps me up all night.
Assuming you're smoking three decent sized full pork butts, you can easily keep those hot (food safety guidelines is above 140*) all day if needed. Preheat a decent cooler (one of those that supposedly keeps ice for three days of more) with hot water or wrapped hot fire bricks from the oven (Alton Brown's idea, not mine).
After smoking, I double wrap the meat (and a little AJ) with foil and add two or three two liter soda bottles full of hot water to the cooler as well. Also, wad up newspaper for any leftover space. Like I said, I've gone all day, about nine hours like this, no problem.
It's always a little tastier right after pulling, so I usually wait and do that in front of my guests right before supper. If smoked to tenderness overnight low-n-slow, there won't be much if any fat or connective tissue to pull out so it's not a big deal at all. It should just about fall apart on it's on after unwrapping from the foil. (I use BearClaws to "pull", but feel free to leave it in chunks if you want. I've had it that way at Big Bob Gibson's in Alabama, which is famous for their pork shoulder, winning Memphis in May, so it doesn't HAVE to be pulled. It'll dry out faster that way, anyway.)
If you've got enough smokes under your belt to know your cooker, you can set it and (almost) forget it, and you shouldn't miss much sleep. If you don't have a remote pit therm, that's not a problem. Just get it smoking somewhere in the 225-250 range measuring at the vent, 200-225 if using the factory gauge (assuming it's accurate). After you feel that it's steady, if using briqs, tap each leg a few times to knock off the ash and set your alarm to go off about six hours later.
Get up and check to see if the coals need stirring (especially K blue bag) or the vents need shutting some. You can go ahead and add some more hot water if you want to as well, but the (2009 and newer) water pan will hold enough water for probably about nine hours without getting too low.
Three butts is a great number for your first overnight cook, by the way. It's harder to overdo the bark on one butt over the pan vs. two filling the bottom rack. The two on the top rack should be done at the same time or before the one on the bottom rack, even if all three are the same size... at least if using water in the pan.
