To each his own, but your use case seems like the worst way to accomplish what you need. There are so, so many apps that will allow you to pin a widget to one of your homescreens with a to-do; why on earth would you want to have that living in your notification shade? I have a Keep to-do widget and the Android battery widget on a second homescreen to the right of the main. Exactly as much work as pulling down the shade, except I swipe left instead of down, and no chance of accidentally clearing the persistent notification.
Rich, coming from the mod that banned me because I called him out on a shitty joke.