Transgendered students often face obstacles in schools that don't even have required uniforms, so unfortunately I think your petition is unlikely to succeed, but I encourage you to carry it out anyway since this kind of change comes in small steps.
Logical arguments don't real work when dealing with discrimination and homophobia/transphobia. These phobias can deeply frighten administrators, parents, and even other students. Their response is emotional, not logical.
Decide how important the issue is to you. If it's mostly a matter of principle and standing up for what you think is right, the petition is a good idea, even if doesn't bring about change. On the other hand if this goes beyond principle, and you or someone you know is depressed or suicidal about not being able to express themselves, then letters from a psychiatrist would be the most effective way to scare the school into allowing it.
Logical arguments don't real work when dealing with discrimination and homophobia/transphobia. These phobias can deeply frighten administrators, parents, and even other students. Their response is emotional, not logical.
Decide how important the issue is to you. If it's mostly a matter of principle and standing up for what you think is right, the petition is a good idea, even if doesn't bring about change. On the other hand if this goes beyond principle, and you or someone you know is depressed or suicidal about not being able to express themselves, then letters from a psychiatrist would be the most effective way to scare the school into allowing it.