Hi folks.
I would try this:
1 - Make a group or a component with the object.
2 - Inside the group or component, I would create another nested group that will contain a simple rectangular box having its dimensions adjusted to contain exactly the object. This is very easy to do with the Rectangle Tool and the Push/Pull Tool using the object itself to control the pulls or the pushes.
3 - I would hide this box.
4 - Then, whenever I need to grab the "bounding box" of an object, I would first show hidden geometry and then move the object using any suitable points on that box.
Of course, using scenes to memorize settings like "show hidden geometry" or not would help greatly. Just a click on a scene tab and I am set to grab and move. Another click and the box or boxes are hidden. Using layers could also be possible to control the visibility of these boxes.
Just ideas.