Very long car trips were something that I did over and over and over when my kids were little and I mean trips that were anywhere from 13 hours to 3 days (we're a military family so we don't always know far enough in advance to buy airline tickets at a reasonable price). The DVD player was a GODSEND!!! Honestly, pick out some of his favorite movies, as well as some that he hasn't seen yet so he doesn't get bored watching the same thing (often my kids want to have their favorites on, but they want to play and do other things while it is playing in the background). I would also suggest that you buy plenty of cheap, but new toys and books (interactive with touchy feely bits are always good), and keep them away from him, like you were thinking, so they are new and very distracting when you pull them out. Also good is to have snacks and treats that will take a while for him to eat.
**A good plan for us was to make sure and pull over at meal times and sit down at an actual restaurant. That way, the kids felt like they were getting out of the car, and we could time it for them, so they'd know when we were going to get out of the car....for example, we'd say, each of your movies is an hour and a half. You are going to watch 2 (or 3) movies and then we are going to stop and get out of the car - even if you just pull over at a roadstop with room for the kids to run around and play. Granted, this adds a couple of hours onto your total time, BUT it was much more pleasant for everyone - and if we stopped at either Burger King or McDonalds for lunch, then the kids could play at their playland and get out some of their energy. I know eating at fast food and then sitting in a car isn't ideal, but I always just got a salad, so it wasn't too bad. Plus, they don't actually have to eat while you are, they can play while you eat and then take their food with them and eat it in the car, so that's an additional distraction for them.
As for the driving at night bit, I would recommend you not do that, especially if you are doing it because you are thinking the kids will sleep through most of the trip. Don't get me wrong, this might work very well for your family, but we tried it and it was one of the WORST mistakes we've ever made. We found it to be far more dangerous to drive at night with the decreased visibility, plus the increase in animals that came near the road. Plus, despite the naps we took to try to be ready for it, my husband and I were both exhausted and our daughter only slept for about an hour of the trip. It was an awful experience. We found that traveling during the day and hopefully them getting a nap was the best way, even with the other frustrations.
Good luck and I hope you have a very safe and fun trip!