Does anyone know how well an Autohome RTT with their added insulation does in extreem cold. Or would it be better if I insulate the interior of the Delica, loosing the space, sightlines, and the everyday usefullness of the van's interior. I need to stay warm at night sleeping in sub-zero temps. Any ideas people, are there any of you who are hardy/foolish enough to camp under these conditions for extended periods of time? What are some of your solutions? Thank You!