at:
the 2: Harding, Erickson (Barcello could play here some if Wade shapes into form & plays backup 1 effective enough to distribute Alex's minutes)
the 3: Lowell, Baxter, George
the 4: Baxter or Lowell, though I agree your lineup w Haarms here is the most likely assuming everyone remains healthy. Practice or early season performance could reveal a stronger lineup, potentially, though. Burgess did mention that George could play here some, too.
the 5: Haarms, Baxter (same reasons given for the 4; I too expect Harward to start here)

I think the only undisputed position heading into this year is Alex starting at 1. But I do like your lineup — assuming Johnson turns out grabbing that shooting guard spot (it sure would be a good sign for the team if he did that, I think).