Treble Clef sounding two octaves below

I write for brass bands. All parts are written in treble clef. You have treble clefs sounding an octave above, two octaves above, and an octave below - but not two octaves below. The bass clef has the full range.
I have the instruments set to sound at the correct pitch, eg a written 'C' for a euphonium sounds an octave below, but it is a nuisance when I switch to concert pitch so that I can write without having to worry about the different transpositions, and the Eb and Bb bass instruments then automatically switch to bass clef, because there isn't the appropriate treble clef.
This would seem to be a relatively trivial feature to add. Any chance?