The foil covered foam insulation isn't as durable as you might think. You'll have to put something over to keep it from gitting torn up from road debris. The aluminum foil will also have a tendency to peel back when the edge is subjected to airflow. A layer of corplast would work...or even some aluminum flashing is possible. Fer better durability...fiberglass over it might be a better choice.
I think the the max temp on it is around 250?F...slightly higher than coroplast. I used the ?" R-Matte foil based sheets.
I will be using this as a filling in a coroplast sandwich it fer my aerocap.
This is my belly pan thread over at ToyotaNation.com. My test material was luan board since it was around $10 fer a 4x8 sheet.