This trip is unrealistic as you have 16 destinations in 28 days, and many of these destinations would merit stays of 3 days or more. You're coming during the summer travel season when school vacations boost the crowds and prices for popular destinations. Consider eliminating or minimizing your stays in the major cities of the Northeast Corridor (Boston to Washington, DC) and saving them for a spring or early fall trip at a later date, especially as you want to emphasize camping on this trip. Ditto, for Chicago and perhaps Toronto and Montreal.
There are some great campgrounds at Niagara Falls, check on the forum there.
http://www.tripadvisor.com/SearchForums?ff=97&geo=154998&scope=2&q=camping&x=18&y=10&s=+
From Memphis, consider the Mammoth Cave National Park, Bourbon Trail and bluegrass horse country in Kentucky.
In Ohio, consider visiting Dayton, OH, to see the excellent U.S. Air Force National Museum, the largest aircraft museum in the world, and the Dayton Aviation Heritage National Historical Park. In the latter, you can see the Wright Flyer III, the world's first airplane capable of controlled and reliably sustained flight. It was perfected and first flown in 1905 at Huffman Prairie Flying Field, the world's first airfield.
Cedar Point in Sandusky, OH, is the world's roller coaster capital. Camping is available nearby at the excellent East Harbor State Park, right on a beautiful Lake Erie beach, but make reservations ASAP. Short ferry rides will take you to the Lake Erie islands. Kelleys Island has a charming state park campground. Put-in-Bay on South Bass Island is a regional party island dubbed the Key West of the North Coast; it also features the Perry Victory and International Peace Memorial, celebrating the American victory in the Battle of Lake Erie and centuries of ensuing peace between the U.S., Canada, and the U.K. along the world's longest undefended border.
http://en.wikipedia.org/wiki/Perry%27s_Victory_and_International_Peace_Memorial
Cleveland has the Rock and Roll Hall of Fame, West Side Market, good mass transit, and an easily visited and excellent downtown professional baseball stadium. A new hostel is scheduled to open there this spring, close to an RTA rail rapid station and the West Side Market.
Ohio Amish country is two hours south of Cleveland with many nearby camping opportunities and a youth hostel at a personal favorite -- Malabar Farm State Park. Or check out Mohican State Park if you like swimming.
As you continue to Niagara Falls, check out Presque Isle State Park, with the best U.S. Lake Erie beach complex. At its entrance is the admission-free Waldameer Park, an old-fashioned "street car" amusement park where visitors pay by the ride. Waldameer features one of the world's best coasters, which travels across a freeway.
Enjoying Lake Erie before visiting Niagara Falls is a good idea because the lake dies violently at Niagara Falls.
Allow at least 1 1/2 days at Niagara Falls, likely two nights, for a June visit, heading to Niagara-on-the-Lake for a Whirlpool jet boat tour (sit in the front on an open-air boat and bring water shoes and a change of clothing) before continuing east.
Check state parks along your route for typically excellent and bargain-priced camping sites. Here's the link for Ohio:
http://www.dnr.state.oh.us/parks/parks/tabid/726/Default.aspx
Make state park campsite reservations ASAP, especially for popular locations such as the Sandusky/Port Clinton area of Ohio.
Definitely read through this forum for the last 3-6 months. Most of the posts are for the West and recently for Leaf Turn vacations, so you actually will have a short reading list.
Good planning!