yes adapter donut fits into what comes with ford truck and provides a surface 1/2 inch above ford bed upon which signature rests so0 nothing is crushed. Thus all of the signature will sit above the bed on a 2011.

I am not sure if Ford simply raised the 2011 bed to keep the Reese stuff below the bed or if there is some fancy solution under the bed so 2008-10's and 2011's have same bed height.

The same amount of "meat" is needed below the bed to keep the hitch firmly in place. Since the spacer donut acts like a 1/2 to 3/4 inch washer with no holding power longer "bolts" are needed.

The kit also has some nuts and locking pins similar to what comes on a regular signature.

It is hard to tell but I think if you just put the adapter donut on top of the 2011 donut that comes on the truck the resulting donut sticks up above the bed a bit more than the aftermarket donuts do for original signature series. Alll of the pieces in Ford's adapter becomes an integral part of what comes and goes with the hitch (the adapter donuts/spacers, longer bolts, and lock nuts all come out with the hitch).

When you have the parts in front of you it is very obvious how it works.