This is the type of topper I'm looking at. They are $1200, so I don't want to mod one too bad. They are also fiberglass and painted to match.
Those "balloons" wouldn't be bad. I could deflate them when I let the door down. Heck, I'm guessing on 2mpg which would be a 25% increase. I think that will be the best bang for the buck now and I'll start on the sides/rear of the trailer then start on the front of the truck.