Turns out, it wasn't nearly so difficult.
If you go to your Display Settings and scroll all the way to the bottom, you'll find a new checkbox for "Edit your writeup directly in the display view, instead of in a separate page".
If you turn on this option, you will get an "update your post" edit form directly below your normally displayed post. Note, however, that the writeup edit form is now separate from the voting form, so that the surprising behavior documented in the OP will no longer occur.
I reckon we are the only monastery ever to have a dungeon stuffed with 16,