I built this rack for under $100 in steel.
Right now, it only mounts at the four corners where the factory roof rack bolted down.
It's made of 1" 14 guage square steel tubing and has an expanded steel floor. Brackets were made of 1/4"x1" steel flat, as were the supports for the fairing.
It measures 72"x40" at the base, and is about 8" tall.
As a quick hack for my trip, I bolted two yakima bars to the top to easily mount my yakima snowboard holders.