WebScrapBook 2.12.0 has reworked the strategy of handling constructed stylesheets so that they don't duplicate among each referenced shadow DOMs anymore.

In my experience, I have found that using the SingleFile chrome extension does exactly the task that I'm after (almost), and it does it best. It's able to save the page precisely as it looks like to the user during a live render (even when viewed offline), and I've found that it's better than both the "Save Page WE" and the "WebScrapBook" extensions.