I'd start all three. Use full backs for width and have Doku and Marmoush looking to attack the space between their full back and CBs to create more room. Grealish is so good at drawing players onto him to create room for others so I'd use him more centrally.
Might work, but KdB is likely to play, as is Haaland. It depends on how Pep sees Haaland's importance for the next league game. If he thinks he's irreplaceable vs. Bournemouth and drops him, then your plan becomes more realistic.