Here's the RV Parks Review on the park...reading carefully.
Cahokia (Illinois ) - Campground Reviews - RV Park Reviews
We have family in St. Louis and stayed there about 10 years ago. It was awful with our 33' 5th wheel - cramped sites, rundown park. I don't know if they've improved anything but we wouldn't recommend it. If visiting downtown St. Louis is your purpose, Casino Queen RV in E. St. Louis is probably better after reading past posts on it. But if you really want a pleasant camping experience for visiting St. Louis, try to get a reservation at Edmund Babler State Park. It is an easy drive into the city (during non-rush hours) and is many acres of lawns and trees. The sites are huge, it's excellent for biking riding, walks in the forest and there's even a swimming pool. There are 2 campground loops and one loop is not suitable for you motorhome. Our site preferences with our 40' motorhome (in order) are: 22, 20, 21, 19, 18, 23, 16, 24, 15, 14, 11,10, 8, 30, 27. If you go to the web site www.mostateparks.com
each site shows details. They do have unreservable sites also but you'd have to come into those on Mon or Tues and preferable after school starts. This is a popular, busy park. Good luck!