All good suggestions here. But my best advice (and please don't take this wrong) is to try to avoid the situation by leaving earlier, adding another stop, overnighting at a Walmart, etc. As a still-working stiff I know this is not always possible, but frankly my greater concern are the poor campers on either side of you who have to endure this challenge along with you!
Sure, if it's still fairly early (5-9pm) that's one thing, but we've been awakened after 11pm more times than I care to count by some poor soul who just drove all night to get to a campground (usually on a holiday weekend and after working a full day) and just wants to get in & hit the sack. But as we lay in bed listening to a rumbling diesel taking much longer to back in due to the conditions combined with short tempers & shouted commands it can ruin the better part of a good nights sleep...particularly if you took pains to avoid the same situation! And then of course follows hooking up the utilities, unhitching, leveling & jacking, and all the other set-up rituals that are incredibly loud when it's quiet at night. Not to mention all the flashlights waving around & into your windows & God forbid scare lights blazing on both sides!
Then to make matters worse; if the late arrivers want to decompress a bit ( and who doesn't - you're on vacation, right?) a fire is often built, adult beverages consumed, discussions had, even music turned on, etc. You get the picture: one time at a state park it was well after 3am before the folks who came in late finally shut the hell up! And before you say it, no, I'm not going to walk over & ***** to them or try to find a camp host or park ranger. Not worth A) the risk in today's well-armed society; B) setting a nasty tone for the rest of the trip; and C) good luck finding an authority at that hour!
Ok, curmudgeon mode off.