I had to mount mine at the very top edge of my trailer, this made it very tall. I knocked off a few inches from the bottom of the top bracket and it's perfect. Also, the edging on my trailer is not very square so I had to force the brackets outward to make them plumb. With the extra outward force I decided that the set screws might not be enough so I used a self tapping #8 x 3/4 screw between the two setscrews and on the bottom side of the cross beams. The rack is crazy sturdy and secure. It was a very simple install and took very little time to accomplish. I love this rack, it's the exact same as the other 'name brand' racks but way less expensive. Don't let the price fool you, it is rock solid.