Interesting and ingenious idea. I don't think I would want the Normal style given an outline level, myself. That is going to really mess with the document structure.

In addition, although it may be three spaces in the definition, there are not three editable spaces in the text, just the block of space.

I would recommend using Graham's macro instead. It is less likely to result in other issues both with your document and your publisher.

Here is the definition dialog which you reach by pressing the "More" button.
00 deleteme 1.png