@Heather: The document I used for the SME review process was one I created myself in a Google document, not using Storyline. I used the Snipping tool to quickly grab screenshots for the document.
@Curtis: I'd say my storyboards have been somewhat like rapid prototypes because I often go beyond just having the "next/back" buttons and set up actual functioning navigation, to ensure everything I want to link works, and that the flow is there.
For the question about SME's who work off-site or remotely, that's a really good one. I've used Google Docs in the past, and there's some other discussions in the forum about how our community members achieve this:
https://community.articulate.com/discussions/how-sme-review-storyline-projects :) hope this helps!