Sorry about that -- was writing mine while you submitted yours!
We ran into that exact issue at work.
There's a couple workarounds that were tried:
1) p.indent style that uses margin-left to force the paragraph to match the item indentation.
2) li.clean style that, as you described, removes the bullet/number from that step in the list.
The issue with #1 was that it made creating long lists extremely tedious, because you'd need to break and continue the list over and over.
The issue with #2 was that you needed to start renumbering numbered lists every time you broke it with the li.clean style, which was again, very tedious.
We ended up settling on this method: Using the Ctrl+; shortcut to add a paragraph element to a list item. The easiest flow of the process for us ended up being:
1) Enter text in the list item.
2) Press Ctrl+; to create a paragraph inside the list-item (which automatically includes the text.)
3) Press enter. A blank paragraph, indented, is automatically added.
4) Enter text in the blank paragraph.
5) Press enter. Another blank, indented paragraph is created.
6) Press Shift+Tab to return to the list item level. (If you're in an unordered list, this will add a new bulleted item. If you're in a numbered list, this will add the next number in the sequence).
The issue you may run in to is that padding or margins applied to the paragraph element, either by your stylesheet, or by the browser, can cause weird spacing in the lists. That's a pretty easy issue to resolve, by defining implicitly in your stylesheet that paragraphs inside list items won't require extra spacing. Here's a jsfiddle demo -- this assumes the most aggressive application, that all paragraphs in all list items won't need margins or padding:
https://jsfiddle.net/MattyQ/byytwu17/