It would be great to store the value of a checkbox to a bookmark, which could automatically open the related bookmark in a Private Window. Presently, one has to know in advance/remember it and must manually right-click the bookmark to select the "open in private window" option.
I'll give you one specific case. I subscribe to 2 different italian online newspapers but, sometimes, I need to compare the way the same piece of news is presented by other newspapers. It so happens that most of these newspaper sites count the news you visit as a guest and, after showing you just 1 or 2 pieces of news, they dim out the window and invite you to subscribe. Months have to go by before their counter-cookie expires!
But by reopening the bookmark in a private window, their counter always starts at 0, since cookies didn't get stored in previous sessions.
As already said, if there was a reason to implement private windows, the same applies to "private" bookmarks. I am sure there are many cases around the world where one needs to reinstate the same "protection level" (situation) later. Someone even implemented a plugin (see above) to overcome such missing option. The plugin works fine, but whitelisting sites, one by one, is a tedious (and extra) task. Regards