Well, I obviously cannot give you first hand experience....but since your post is an orphan (likely due to the fact that the current American Dream has not been around very long), I'll just say that even vintage American Coaches have good insulation and are well constructed.
Heated tanks for sure and no doutbt Hydro-hot on the 2019 Dreams.
Fleetwood is touting their insulation on all of their 2019 DP's, so I imagine it is light years ahead of our vintage Eagle.
We don't get single digits down here, but have never been cold while camping in the winter in North Florida.
1998 American Eagle 40EVS