We stayed in site #59 for memorial day weekend. 

The campground is pretty close to the freeway, but you can avoid the noise if you stay on the opposite side. The freeway travels along the outer ring of campsites in the #70's.  I included a google maps picture of where the freeway is in relation to the campground. We tent camped at campsite 59 and it was just a bit loud, if it was louder I would maybe not have enjoyed our stay. After a couple minutes, it just became background noise and we didn't really notice it. If you are looking for the absolute farthest sites from the freeway, they would probably be anything in or near the sites in the 20's. 

Our campsite was very nice and spacious. It was well shaded near the firepit and mostly hidden from next-door neighbors. The site is just across the road on a diagonal from some vault toilets. The toilets were surprisingly very nice, always clean and no smells. However there were a lot of mosquitos in this park. So many that we drove to Walmart and picked up some 2 Thermacell Patio Shield Mosquito Repeller, they actually worked great. 

All in all, I was a bit nervous that camping in the dells was going to be undesirable, but it ended up being a great weekend. We really enjoyed that you can drive anywhere in downtown dells in less than 10 minutes. I was shocked that the strip was so close to the campground because after getting off the freeway and to get to the park, you felt like you were almost in the middle of no where.