I keep my registration and insurance card in a sealed baggie under the seat, so far no problems. I also kept my "elastic cargo net" there, but after less than year it broke; it was either defective elastic or the heat got to it, I've never seen a rubber band or anything deteriorate that quickly. My twelve-pack of bee.. uh, "coke" almost fell to the street! 
There is a thermal insulation tape that you can add to the bottom of your storage compartment, for extra protection.
There is a thermal insulation tape that you can add to the bottom of your storage compartment, for extra protection.
