Margin problem with hidden staves

Problem in short:
When staves are hidden, the left margin still makes extra place for hidden staff names, which is unnecessary and looks bad.

Detailed example - see attached file:
This score has 4 instruments : 1 "voice" but that has NO staff name nor short name, and 3 clarinets (that have staff names and short names).

Bars 1-2-3 is music on staves with names (clarinets),
Bars 4-5-6-7 is music on the staff without name (voice).

I hide empty staves, so that system 2 only shows music on the voice staff, without a staff name.

BUT although there is no name to show, the staff still starts with an extra left margin because of the staff
names of the hidden staves. This is unnecessary and looks bad. How can I make the system start on the
(real) left margin, when there are no staff names to show?

An easy fix would be to delete the short names of the clarinet staves, but I still need these short names for
music that would be written after this, in a longer file. This is thus not a solution.