Steve, I've been contemplating the same install. I have the same concern. I've been casually looking for some type of anchor that would stick in that insulation, Styrofoam, in the ceiling. Most anchors will just turn, in my experience, without holding when trying to install. I just ran into the same issue under the motorhome when I had to reattach my Hydrohot exhaust pipe. Let us know how it turns out. Thanks
Jerry