Have Shuster and Siegel ever cameoed in a comic?

Question

I'm trying to find out if Shuster and Siegel ever put themselves in one of their comics or if they've been cameoed by other artists/writers?

Either as themselves or as characters easily recognised as them.

Answer 1

Action comics #554, "What if Superman Didn't Exist?" -- there is, I believe, a homage, but it was not drawn by Schuster and Siegal, so I don't know if that would count as a cameo.