We do this often. Bring extra clothes, just in case. WE always save one clean outfit for the ride home. We don't travel too far, but driving even 30 minutes with grit in your undies is no fun. :)
Baby wipes work well for clean ups. Hand sanitizer for before meals.
Make sure everyone has their own flashlight..it will save you arguments in the end.
We don't have an air mattress, but one of those would save your back. We do have individual mats for our sleeping bags. My mat and hubby's inflates just a bit for more comfort.
We always bring a few things with the kids in mind. Bubbles and a ball. We also bring buckets. One of our camp sites is near water and has a bit of "beach" area. Otherwise buckets are great for collecting treasures. We also bring our horseshoe set..grownups enjoy that as well. And we have a ban on all electronics (except the gps and emergency phone), so we usually bring a story book to read by flashlight after it gets dark. And I stock up on the glow stick necklaces at the dollar store. If the kids are wearing those, they are easier to keep an eye on when it's dark.
We try to keep meals filling, but simple. Often it's hotdogs. But we also prep fajitas before we leave and eat those. OR hobo dinners. If you do all the prep before you leave, there are lots of things you can cook. For breakfast, if we feel like cooking, we make breakfast burritos. Usually we don't want to mess with building a fire (we live in Texas, it gets hot early), so we bring things like granola bars, fruit or cereal bars. And obviously, you have to make s'mores! Freeze half the drinks to help keep things cold. (Only half so you have some to drink if you want).
Don't forget hats, sunglasses and sunscreen. ANd a first aid kit. Ours has all the stuff for boo boos, but other things as well. Meds, benedryll, ear drops, chap stick, cortizone creams, etc. Basically stuff we needed on other trips and didn't have. When we get back I add it to the first aid kit.
Have fun!