Both options sound very sound... actually sounds very natural to have the exact same flexibility there that we already have by curating normal content.
And on top of that proposals have already a post associated, so the first vote could even be automated, as in... what you vote the post of the proposal gets automatically voted on the proposal too (and later on, you can change if you changed you mind). At least will make more people that are just voting for the post, to also mimic that transfer to the same sentiment on the real proposal. And yes, I know its not really the same thing, but for most that don't know, it would harvest a lot more of participation.