That sounds about right to me for southwestern Ohio (not a lot different terrain) - however, if you're not sure about your abilities, choose a trail that offers a "bail-out" point about 4-6 miles in.

Alternatively, head to a car-camp. Load up all your gear in the morning, and head out on a 10-mile loop that brings you back to the car that night. You'll be simulating a "real" backpack by carrying everything, and you'll get the chance to try out all the skills and equipment during the day (maybe that water filter isn't as easy to use as you thought? Or using a cathole takes some practice?), with the safety-valve of a car if something goes badly wrong. If that trip goes well, head out "for real."

Have a great time, and have fun.