Concert etiquette: Holding up signs

Question for people who have held up posters during ARMY TIME!

I’m going to a show soon and I’m in Row 1 in the 100s. I have an A3 poster to hold up during ARMY TIME. But at my last show, a girl had a poster and people around her were actually yelling at her to sit down because she was blocking their view, so I really don't want to be that person 😭

I’d have to stand to hold it up properly, but I’d be super noticeable and I don’t want to block the people behind me. If I stay seated and hold it above my head- I’d probably block them too.

For people who have done this before: what’s the etiquette? Appreciate any suggestions!