I'm for option 3, let us set the AOE toggle elsewhere, and the spells cast will be based on whether it is AOE or not.

I am currently using alt and ctrl quickbars as if they were regular quickbars, and "casting" macros (spells) using those, the game does not display the toggle, so I have a macro to toggle AOE.
If only this system was implemented for regular quickbars, but with the addition of an on-screen toggle or a key to toggle AOE, I think most would be happy.