Hello,
I am amazed how well insulated my 98 XL is. It has been near zero and 17 below last night. I kept my Aquahot on, and toe kickers and and set them so it was 70 or so degrees inside.
Kept my water bay heaters on, but left off my front two bays as there is nothing that can freeze in them. Without heaters on they stayed way above freezing. 45 or so degrees.