This is a pretty common question, but I have a very specific question as part of this. I like to do 4 season camping and would like to insulate my van very heavily. Still, I would like to do so without losing a lot of interior space - the Astro is a wee bit small. I was thinking of putting rigid styrofoam foam on the outside of the van and covering it with fiberglass. I can fill in the interior panels, put 2-3 inches of insulation on the sides and 5 on the top - have a nice toasty warm van in the North Dakota winters and a cool, comfy van in the desert summers. I am looking for advice - specifically how to fix the materials to my van without them blowing off while doing 80 mph on the interstate!