Jason Wish submitted the route:
The Burr Oak Backpack Trail (Burr Oak State Park) is a scenic journey up, over and along the wooded hills and ridges that define the shape of the Burr Oak Lake’s shoreline. For the majority of the trip, the trail is not far from water’s edge. Some stretches of the trail are near lake level, but most are anywhere from a few feet to over 100 feet in elevation above the lake. Ascents are generally short and mild with only a few exceptions, making this a nice trip for beginners.
The main backpack trail is blazed with yellow, and for nearly half the distance along the south and east side of the lake, is blazed with blue as well, indicating a shared route with the Buckeye Trail. The North Country Trail and the American Discovery Trail follow the same route the Buckeye Trail follows through the park. A few shorter state park trails and a horse trail or two also share the main path for short distances, so expect to see blazes of other colors as well, mainly white and red. Some sections of the Backpack Trail are named, probably for the benefit of park visitors and day hikers. You’ll see these names on some signage.
Total distance according to Backpack Ohio.com is 21.2 miles.
Note that the Bobcat Trail Marathon covers the entire Backpack Trail and then some. Anyone claiming a supported FKT for this trail will need to beat the times set in the race.
There is a Strava segment for the Backpack Trail. However, through 2019 the CR is 2014's winner Evan Thomas in 3:28:10 (for the marathon), who's time is not on Strava, so likely there are some faster times still than those listed on Strava.