As predicted, getting WordPress to deal with the niceties of formatting has turned out to be beyond my means at the moment. I have managed to get the layout I wanted by using a fixed width typeface (Courier New) in Google Docs. Here is how the (finished?) poem looks like printed out and scanned:
Below are some embedded Google Docs files. The formatting was fine in the originals but some weird stuff happens when they are rendered here, with some lines slightly shifting out of alignment, and I’ve spent far too long trying to correct the problem. I give up. Hopefully the intent is still reasonably clear.
Anyway, here is the above poem before I dismantled the scaffolding:
And here it is with some punctuation added:
And here it is with some different punctuation and different line breaks:
And here it is, with, like the first (final?) version, William Carlos Williams’s words entirely removed, but rearranged again, to suggest just a hint of underlying pentameter: