Levelling sustain-pedal indications

[PMA]

In a piano page chock full of bracket-style pedalling for chords at
widely different pitch levels, I've managed to align the horizontal
pedalling lines vertically, via a zillion little paragraphs like

\once \override Staff.PianoPedalBracket #'edge-height = #'(1 . 3.5)
sustainOn
...
sustainOff

Trouble is that as a result, the vertical (On/Off) pedalling lines
are all different lengths.  Is there a way to tell LilyPond, "Keep
this vertical *placement*, but don't print the ugly vertical-line
*extensions* that caused it"?

My current plan is to -- later when the dust settles -- white out
the extensions in a PDF editor.

Thanks,
Pete