My typical situation is I have 'my' documents and then 5 further variations of them for distribution to different externals. PDFs alone aren't sufficient for distro, and Styles would be cumbersome and error-prone with 6 doc types in total.

I make a Base doc, the 'my' doc. This is THE doc from which all good things come, so it's carefully stored and backed up. Whenever there are changes to be made, they are made to this Base doc and then a new set of external variants are made.

To avoid this being a chore, and worse, error-prone, I have it automated via macros I access on a custom tab in my Word ribbon. Takes approx 10 seconds to make the 5 variants.

In your situation, do what the guys said above—make your private paragraphs a unique style. If you don't want to have to click the Style every time you write a private para, then 'tag' the start of the para instead, eg with Zxc. When your doc is complete, do a global replace for Zxc and replace it with 'Found What' text and your private style. Then do another global replace of Zxc with nothing. You should of course macro those 2 jobs.

When you want to produce your external version, right-click on your private Style name, select the "Select all XX instances" and press the Delete key. F12 to Save As your new external doc. You could reduce that to one button click also via macro.