he knows that Lu Ten is in the ground, too, somewhere near the walls of Ba Sing Se

You know, I never thought about it, but I don't know why it hadn't occurred to me -- you know that hill we see in Tales of Ba Sing Se? That could be the exact, literal, no-joke hill where Lu Ten died, looking at the city that he had died to help his father take.

We know that Iroh made it past the Outer Wall. I can't deal with the idea of Iroh going back there from time to time while he is in Ba Sing Se.