I see no reason no to do both at the same time. I smoked two 5# turkey breasts (bone in) over the weekend at 230F and they took about 4 hours to reach an IT of 160. The last time I did a whole turkey (13#), I seem to recall that it too took about 4 hours to reach 160IT in the breast. So, I would suggest the whole turkey on the bottom and the breast on a higher rack (if they don't fit together on one rack). If you have only one temp probe, then I would probe the breast and monitor for 160IT. When it reaches 160, remove the breast and check the whole turkey...I suspect it might need a bit more time than the breast, but probably not by much.