This is the first piece I've attempted that calls for sostenuto pedal rather than sustain pedal throughout (assuming I'm interpreting the notation correctly). Other than sempre Ped. in bar 28, the only pedal notation is Led sostenuto in bar 1 and Pedale sempre molto sostenuto in bar 4, all of which adds up to sostenuto instead of sustain throughout I think.
How do I properly use the sostenuto pedal then? I'm thinking play the first bass chord in each measure, then hit the sostenuto pedal, then release after last bass chord in each measure. Is that correct?