Land-Between-The-Lakes (western Kentucky) info...
Camp-wheeling is awesome in the LBL. The whole place sort of caters to expedition rigs. You can purchase a back-country pass that will allow you basically camp anywhere on the island...around $20/week. There are countless fire trails that criss-cross the island and there is always one or two secluded camp spots where they end at the water's edge. These spots are rarely taken, even on Labor Day...traditionally a busy time. You will need to be fully self-sufficient as there are zero amenities in the back-country. The trails are not hard-core but they commonly get rutted, flooded, and blocked by fallen trees. The terrain is deeply wooded with a few steep (but small) ravines. The only people you will see are Jeepers, horseback riders, and the occasional boater that anchors nearby for a swim.
If you need more comfort...there are also numerous "primitive" campgrounds. These areas are usually 10-30 campsites, a nicely maintained pit toilet, mowed & graveled tent sites, and a water spigot. These areas are first-come, first-serve and you pay via the honor system. There is a pay station where you fill out a form and pay something like $10/night. These are supposed to be tent-only but I do see small RV's from time to time. There are no hook-ups, so the RV crowd usually stays away. My wife & I typically stake our claim at one of these...unhitch the trailer and gear...go exploring all day...then return at night to our site. Most of the time there are one or two other campers.
If you need even more comfort....there are three or four "major" campgrounds. These areas are usually 40-300 campsites, and they are divided into RV and tent areas. These are like sub-divisions...they have shower houses, real toilets, fire-wood, ice, camp stores, and all the stuff I personally hate about organized camping (screaming kids, passers-by, street lamps, and of course...GENERATORS!!!). If you need a hot shower...these are the places to stay. The large campgrounds (Hillman Ferry & Energy Lake) take online reservations via the US Forest Service. Beware...their booking system is a total cluster-f**k and I recommend calling via phone to book, or just show up in person. I think a primitive site runs around $24/night.
Turkey Bay is of course...the hard-core offroad area. It is much like the Badlands but without any dunes. This is the only place where quads, side-by-sides, and dirt bikes are allowed...and you will be the minority in a licensed vehicle. You can camp inside Turkey Bay, although I never have. Check ahead for fees, rules, and services...not sure if flags are required, or if they have air available.
There are many cabin rentals available around the entire perimeter of the area...but none on the island itself. So, if you want to stay on the outer shores...plan for an hour to commute to/from the island. There are also boat rentals, a buffalo park (drive-thru), and some other minor points of interest.
NO RESTAURANTS ANYWHERE ON THE ISLAND.
NO BOOZE (DRY COUNTIES ALL AROUND).
NO FUEL. The nearest civilization is Grand Rivers, KY on the north end. I STRONGLY recommend bringing your own spirits and camp food...and make sure to
gas-up before you enter. Its a very big deal to re-stock after you enter...the nearest store can take hours to reach. There is a camp store at Hillman Ferry but, it is limited and pricey. Firewood is available (and affordable) at several places, and there are restrictions in place regarding bringing your own firewood, due to an ash-bore beetle problem.
http://www.landbetweenthelakes.com/
http://www.kentuckylake.com/lbl/turkeybay.shtml