I'm not sure the US Open will be that important to him, it seems plausable that he will concentrate on the remaining clay tourneys like Sopot and Bucharest, where he has realistic chances of achieving good results. Hard courts may become interesting for him again in the very late season and the Australian tour.
I think he will play, Stuttgart Q's, Kitz, sopot, and then go onto the hardcourts to prepare for the US open. The only other thing would be to stay on the clay until 1 week b4 Us open and jsut practise on the hard. I would be very surprise if he dicides to miss out on US open as he has said that his goal was to make MD Us open.