I have no clue if this is going to work well, but neither have I if it's about AngularJS and SEO in general. There is very little evidence it works the way it is supposed to do.
I would suggest leaving PhantomJS in the dark, it is known to have issues and is not very lightweight. Also considering you don't want to write/set up a backend I would use Firefox to use an awesome feature: Element.innerHTML, to capture the html content at any given moment in JavaScript and use the Amazone CDN API to upload the content to a different html page.
The thing that rests is to let the crawler know to index the other page. This is the tricky part since you don't want to have a backend, hence you can't use the ?_escaped_fragment_
url as you said it. I would use just a canonical relation between the pages using a metalink tag. But remember, I am not completely sure it will work.