That engraved brass is a great idea.
I had a similar thing done, but on a Gibson truss-rod cover. I took a high-res picture of a signature from a letter, and had the truss-rod cover made. Nobody really knows (or cares) who it is, but I know. And that was the point.
I've got this buddy - huge Samantha Fish like, super-fan. All Zoowicky could ask me a while back was what was the best indelible marker pen to have her sign his guitar. I finally got him to just get her to sign his guitar strap rather than ruin a Les Paul Custom.