IMO the easiest technical portions of this piece are also musically the most difficult. Take care to study and understand the direction of the music in the less active parts. For the Doppio movimento, I would identify four different parts: bass, LH chords, RH chords, melody. You can practice these in pairs to gain better understating of their interaction. If you do this, make sure to do all permutations of the pairings. I would also practice the RH alone, working on the shaping of the melody as well as distinction between chords and melody. You could try dividing the upper staff between both hands to even further outline the two parts in your ear. There might also be a need to practice flattening the texture of the Doppio movimento to work on rhythm. There are parts where a lot of stuff is going on and competing for brain power. It might also be good to get the section into the fingers and work out basic muscle movements, then later go back and refine the various musical lines ones your hands have a basic idea of how it all goes together.