Better yet, I've used that foil backed foam board insulation (the cheap stuff) to line my RV generator box to cut down the noise and heat (damn designer put the generator right under the main sleeping bed). Worked marvelously. I would say a couple of those duct taped together into a box would do the trick.
Strange, most RVs seem to have a generator that keeps everyone else in the campground up at night, but doesn't bother the owner in the least.
