Thank you! I used around 45 feet of 1/8" wall tubing (including 8x 11" standoffs from the frame)
It was definitely the extra hump that was giving drag. I have driven normal campers before that couldn't really notice. I was fairly surprised that I could feel the drag, but it was a significant difference when I removed the topper.
I am loving the Airaid so far. I cant yet comment on the MPG gains that some claim, but I can feel additional throttle response and early torque. It also sounds MUCH better at higher RPM's, but isn't noticeable at all below 2500 RPM's.
UPDATE
Spot welded the bumper, I am pleased with how it is turning out