Come on over the the Winnebago forum further down the page and get answers from the folks there, who have the same coach.
I have been watching the temps back in southern Michigan(home) and their pretty cold. I have the 2003 DL39QD and I wouldn't trust the system to keep it from freezing until I got to southern Kentucky. Then I would de-winterize there. We came down here to Texas Janurary 3 and had the same thing to deal with.