Need ideas please/correcting behavior

My daughter is two years old. I use a shatter proof mirror strapped to the headrest so I can see her in her car seat (rear facing).

The problem is that sometimes she has been pushing on the mirror with her feet lately (she can extend her leg and reach it) and then the mirror gets angled downwards where I can’t see her. The problem with this is that she is speech delayed and uses signs to communicate. So if she moves the mirror, I can’t see her signs and therefore have no idea what she needs. This causes a problem because then she just makes an “eh eh eh” sound or whines/cries constantly until she gets what she needs.

Nearly every day I’m telling her not to mess with the mirror, but she does anyways. I’ve tried to let her suffer the natural consequences (if I can’t see her signing, I can’t meet her needs and then she’ll just have to cry the whole ride). But this consequence sucks for me too because then she’s crying the whole time (I love her, but that’s not something I want to listen to, you know?) I’ve tried explaining why she shouldn’t push on the mirror with her feet, but that hasn’t worked. I’ve tried telling her no juice or tv later if she does that - but that doesn’t work either (I think that consequence is too far in advance time wise for her to make the connection).

So what other techniques can I use to get her to stop messing with the mirror?

*I don’t want to forward face yet because it’s not as safe, and there’s no other place I can put the mirror because it’s strapped to the headrest.

ETA: she sits in the middle and that’s where the mirror is attached (the middle seat headrest). I can’t get it angled to see her if I attach it to another seats headrest.