I suggest a preview on the mobile page. For questions, answers and edits to both, like on the desktop page.
I messed up formatting often enough to be annoyed that there is no preview on the mobile page and I'm surprised that noone suggested it before (at least I didn't find anything).
If it's too performance heavy to have a live preview update after every change in the text box, there could be a preview button next to the save button which leads to a page with only the preview, a back button and a save button (and the title bar and so on).