dpillI've got an Ergotron LX dual stacking arm. It comes with two mounting options - an adjustable clamp that fits over the edge of the desk (not sure the max thickness of the desk, but I'd guess anything 2.5" thick or less would be no problem) and another that allows you to mount through a hole (such as the common cord hole, or something similar you could drill yourself. When I was laid up with a broken leg, I mounted it to the coffee table and worked from the couch for 3 months. Two other points about the Ergotron - it can be used in a stacked configuration or a side by side configuration, and I've used it with standard 23" monitors as well as ultra-wide 29" monitors.