Excellent suggestion Uncle Bob! I'll have to look into that foil/bubble stuff.

What do you mean by construction adhesive? Is that the stuff in the tube you apply with a caulking gun, for wood adhesive? I wonder how that works with the inside temps of a vehicle in the summer? I like the idea of saving a buck as that 3M #90 is plenty expensive. If I have enough left over after gluing my new headliner on I may still go the 3M route.