Terrible's Lake Side Casino is in Osceola, Iowa. There is an exit off of I-35 that will take you right to it. We have not stayed at their RV Park but have driven through it. The sides are full hook ups and pretty roomy with small trees. The cost is $20 per night and you get $10 worth or slot tokens back making it $10 per night. I don’t know the limit of nights. It is a very clean set up.
The casino is pretty nice and they have a very good buffet. The other items on their menu are also above average. There is a hotel attached to the casino and we have stayed there in the past. I was very adequate for our needs.
The problem with the RV Park is on the weekends you have to get there early in order to get a spot. It fills out before evening. The lady told me it would be a good idea to get there around 1:00 on a Friday to get it. They do NOT take reservations.
If you can get a spot it would be a very nice spot to spend the night if you are going north or south on I-35.