If you have a lot of apps installed as I do, it would be helpful and save time if there was a 'select all' check box in the header of the apps table hide/don't hide check box column. See moch-up screen shot below of Preferences Focus Mode tab.
The AdBlock for Safari App has got two Safari App Extensions: one for basic ad blocking functionality, and a second one (comes together with the app) that sets an icon in Safari to manage ad blocking details for every single page. With this icon (at least in older versions – I'm not sure whether or not it's still there.) you could block elements of the page like pictures, frames etc. from beeing displayed or printed. That seems to be exactly what you are looking for.