Ten years ago, when we wanted to stop in St Louis and visit the Gateway Arch, we camped here.
Casino Queen RV Park
Back then, it was nothing fancy- kind of like camping in a Walmart lot, but with full hookups. However, for our mission, it was great. The CG had a free shuttle that would take you to the casino or to the light rail station where you could ride across the river to the arch.
Later that evening, my wife and I came out of the casino about $114.00 to the good. We never got to keep the money, though, as the next day I had to buy two new batteries for our TV when it wouldn't start after stopping for lunch in Indianapolis.