We stayed at the Fon Du Lac KOA in September 2021 for an overnight. If just passing through, this is a pretty interesting campground. It met all of our needs and we enjoyed the visit very much. It's a very large campground and for an overnight, it was very nice.
We showed up right when the campground was having an event so lots of activity going on right then, kids running from campsite to campsite getting candy and such.
The campground (the section we were in) was pretty much all seasonal campers. Folks knew each other and had a social connection going on. I could tell they were not just strangers, but actually neighbors and friends.
We were parked on a gravel spot. Management was very friendly and helpful. We had 50 amp service and water. (I don't remember sewer hook up though. That might have been one of those time we simply "too it with us" rather than bothering getting out the hoses.)
It was quiet at night. It is off the main road quiet a lot. It's not near any interstates or highways where you hear road noise all night.
For an overnight I think this campground will work well for you.
I can't remember what all of this was all about