I modified a local copy of dominos to only take control of action bars 3 and 4, and to not hide the blizzard UI for the main action bar, the bag bar, and the menu bar. It works well enough for my purposes. The bulk of my changes are trying to undo some of the assumptions around which button ids are available to dominos - instead of the first N buttons, I only allow access to a set of button ids. I think theres more work to be done in the blizzard hider plugin - specifically allowing toggle of hiding an element and exposing this in the config panel.

I wonder if you think this concept could be further developed and merged into dominos? Or do you know of an addon that would make more sense for my use case?

This is maybe something to consider for the next expansion (where they're revamping the UI)