Free Camping in Indiana
For those campers who love the freedom and allure of sleeping beneath the stars and not paying a dime to do it, your best bet in the Hoosier State is to explore the roads of Hoosier National Forest. Outside of that, free camping is also available via business parking lots along the northern stretches of the state.
Free Camping in Hoosier National Forest
The US Forest Service permits camping on its public lands in Indiana, free of charge.
The limitations are specifically that you cannot camp for free in established campgrounds and that you must stay within 125 feet of the road. The USFS doesn't provide maps to these locations; however, they're often clearly marked and with a little exploration, should be easy enough to find. One example is crowd favorite Blackwell Horsecamp, which is primarily aimed at equestrians but has no official rules barring those without their trusty steed from camping there. Fire rings and vault toilets are provided.
Just note that there is a 14-day limitation on camping within the national forest, and before driving down dirt roads, you should have a good handle on how to boondock properly. When looking for free campsites, for example, the first rule of thumb is to find an already established spot so as not to damage the forest you've come to enjoy.
The forest service also provides free dump stations near Branchville, Indiana.
Free Camping in Casino Parking Lots
Where free camping areas may feel a bit sparse across the state of Indiana, for those who love to play the slots, there is ample concrete available outside of the two casinos found along I-80 / I-90 running along the northern border.
Blue Chip Casino has plenty of RV parking available and, aside from the casino itself, is not far from Lake Michigan and Indiana Dunes National Park as well. It's the preferred "campground casino" of the two among Campendium users, but Four Winds Casino near South Bend is another option.
Should a trip to Indianapolis be your goal, a parking lot by the name of Harrah's Hoosier Park Racing and Casino is about 45 minutes from the city's center and allows RVers to stay in a lot specifically meant for such an endeavor.
Anytime you're camping in a casino parking lot, you should make sure to call ahead and confirm that it's okay to stay, as some casinos will require that you visit their establishment (and some will give you some credit to get started, too!) while others may be okay with camping except during busy times.
More Free Camping in Indiana
If all you need is a safe place to stay and somewhere to put your RV for the night, businesses across the state like Walmart and Cracker Barrel often allow overnight stays.
Finally, the RV Hall of Fame and Museum in Elkhart, IN, allows for a one-night stay for free and does ask that you visit the museum as well. Still, given your mode of transport and the subject material, that doesn't seem that hard to swallow in exchange for a place to get off of the I-80 / I-90 corridor for the night.