Now that the SLF can no longer be usefully canvassed for ironmongery suitable for penetrating interior panels, it may be time to stump up for a couple battery operated drills with hole-saw attachments sized to admit a fire extinguisher nozzle.
The panel does help keep the halon concentrated where it is most needed.
And definitely the cabin crew needs to know where
not to drill holes
Markings to indicate vulnerable bits immediately beneath or alternatively
Drill Here marks would do that.