Just thinking …
When you want to use the gizmo for posing - you have to MASK
What if the gizmo had a option to AUTO mask everything of the mesh in NEGATIVE Y direction from the origin of the gizmo ? (+ a blur slider).
So you place the PIVOT and everything in negative Y direction is AUTO masked 
.
You only have to pose … then move pivot to next position and pose the next part.
So NO masking needed … because of AUTO masking.
Like a movable MONO Bone PIVOT 
As I said - just thoughts…
