Lafayette, huh? Head pretty much due south to Crawfordsville - a bit southwest of Crawfordsville (15-20 miles) is a state park called Shades State Park. It's got some incredibly beautiful terrain, with trails running along the bottom of some ravines down to Sugar Creek. There is some moderate elevation gain and loss. The public campground is Class B - most people tent-camp - no Chinese Lanterns and big RVs here (they go a few more miles to Turkey Run State Park, which is a resort park.) Best of all: about 2 miles out, accessible only by foot, is a backpacking campground. It is on a bluff above Sugar Creek, and has a water faucet and nice privy. It's a great place to practice backpacking technique and get comfortable with your gear, without having to go full-bore dealing with water purification or waste disposal. (There are plenty of streams where you can practice water purification, though.) It's not crowded, and is one of my favorite places. It's safe (if your tent fails in the rain, or it turns unexpectedly cold, an hour's walk from the backpack camp gets you back to your car) - I used to bring Scouts here for their first overnight backpack. But it still feels "wild" - I remember lying in my tent one night in the backpack camp, listening to a pack of coyotes a mile or two off to the west, and getting a shiver down my spine when another pack answered, about a mile to the east - and I sincerely hoped they didn't decide to come meet in the middle!
Send me a private mail with your email address, and I'll send you some trail maps and other information about the park.