Instrument Playback

I have a situation where an instrument is playing in the wrong register, in this case a contrabass saxophone. The playback sounds the same as the baritone saxophone. I am scoring everything in concert pitch, not transposed. Do I need to write the part an octave lower in the bass clef or is there a way to modify the playback so that I do not have to write the contrabass so far below the staff?

See if your VST has the ability to transpose the instrument down an octave there (HALion does).