Our first TM was purchased in 2000. We took it to Silver City, NM and spent the first three days in a wind, sleet and snow storm. Worked great. We kept warm and didn't even use additional clothing indoors.
I have a video somewhere of being indoors during that storm. If you check the Trailmanor website you'll see that the wall, ceiling and floor insulation is the same if not better than most rvs. The floor especially.
We had two TMs but I wanted to be a big guy and roll like the rest. Sorry we sold the last TM. Sure would love to have one now.