I went to Loudon last year and Dover a couple of weeks ago. Nascar camping is field camping, tightly packed. Our group always forms a bit of a "compound", as long as the organizers let us park that way. We had six or seven rigs this year so we got extra spots so we had room to organize ourselves plus lots of space for our trucks. Otherwise, as I mentioned, it's pretty tight.
It's all dry camping, so lots of generators. In my experience you have to turn them off at 11 unless you have a note from a doctor that you need to run the generator for a sleep machine. Companies typically go around offering ice, water filling, pumpouts, etc. At Dover there was a place to go for free fillups if you wanted to do it yourself. They also had a dump station a lot of people used when leaving, but I don't know if it was free or if they're widely offered.
It can be a really good time at the campground, with lots of fun things going on. I think the infield might be neat but it would be really LOUD when the cars are running, which would be every race that weekend and any practice time. Most camping areas are a reasonable walk to the track plus there's often a shuttle service. I've also seen people use bicycles to ride back and forth.
We also buy extra seats for the race, so we have lots of seating room there too.