Hi niquebs,
I'm glad to see that you're getting involved in this wonderful community, but this question has been asked / suggestion has been made several times before (it's possible to search through old posts from the website).
One of the existing posts on this topic is the great suggestion of a solution to this problem using GitHub by @lukestokes: working-on-a-long-steemit-post-save-the-draft-as-a-github-gist-file