I created a small plugin to help with this situation. It doesn’t try to automatically do anything, but provides a couple of functions and a toolbar button to automatically arrange the view in a side-by-side split mode (edit/preview) in either horizontal or vertical layout, and optionally (on by default) close any other unrelated panes.
Another hotkey can be configured to specifically call the “close all other panes except the active one” function for convenience.
I submitted it for review, so it will hopefully be available for download shortly. For now if anyone wants to test, just download the release and pop it into your Obsidian plugins dir…