To answer truthfully, I do not Know because any of my ideas would bang right up against the First Amendment.
But THEY are preventing Peaceful Assembly, so maybe not allowing and confiscating signs might be allowed.
Thanks for trying to think of something. I know years ago, I went to an election rally/Dick Cheney event here in Denver. I didn’t see any disruptors inside, but smatterings of them along the streets away from the event. I’m pretty sure I remember correctly, but only Repubs got called to notify then about tickets. It was fairly tight security. Of course, Bushie/Cheney were already in office at that point (2004). Not sure how it would work for someone just running.