You're right Harry's mood is some evidence for his having the body. And from his behavior I think it's clear where it is:

"The gem upon your ring," Dumbledore said. "It is no longer a clear diamond. It is brown, the color of Hermione Granger's eyes, and the color of her hair." A sudden tension filled the room. "That's my father's rock," Harry said. "Transfigured the same as before. I just did it to remember Hermione -" "I must be sure. Take off that ring, Harry, and place it upon my desk." Slowly, Harry did so, removing the gem and setting the ring off to the other side of the desk. Dumbledore pointed his wand at the gem and -

From this and putting the ring as far away as possible I'm pretty sure the body is the ring and the rock sits on it to fool the magic detector. Someone called it in the comments on last chapter, when I get a chance to check I'll edit their name in so they get the appropriate Bayes points.