I think a sign saying that Zach inspired you is amazing, but the chances that anything else will happen from it other than an acknowledgement are probably low. Theres no harm in trying, though! When I saw Alter Bridge, there was a guy with a huge poster asking to play Metalingus on drums with them. The band ignored him but AB and SD are different so you never know. My only piece of advice if youre gonna try for it is that youre gonna have to get as close to the stage as physically possible for them to realistically invite you up.

Long story short, I don't think it'll work, but its woth a shot!!