Why does the alignment label matter in that campaign? If people are having fun doing things that endanger their character, why can't YOU have fun endangering their character?

Heck, if people are doing stuff that endangers the party, claim that your CHARACTER thinks it is deliberate, that the crazy character must actually be in league with the wolves, or the giants, to the point that they would sacrifice their lives to the cause. Make it clear that you as a player are fine with it, but that your character is less imaginative than you are, or something.

Or just have fun playing lawful snark, or even lawful evil, if you MUST play with labels. Why in the world do you need the GM PERMISSION to change alignment? Do players need GM PERMISSION to be stupid? No? Then why do you need GM PERMISSION to be interesting and fun to play?