dedicating a day to insulting the prophet isn't going to achieve that, it will only make them more hardline.
enaging them on the fact that they've made the prophet into a idol would bare more results.
I have no faith in these people being converted via rational and reasonable means. The fact that they don't realise their idolatry is un-islamic isn't going to sink in if I tell them or if you tell them. The only solution is to outrage them into boredom. It's hard to maintain a hardline stance when the rest of the world clearly tells you to fuck off and won't pander to your 'outrage'.