I am making a monitor lift using the c-beam linear actuator and 20x40 linear rail. The actuator will be mounted the desk and the rail is attached to the gantry plate. I found a mounting plate that looks like it will work but I don't know what size to get. Vesa Monitor Mounting Plate I am thinking the 40 series is the right size but I don't know enough to know for certain that it is the right one.
What about http://geldner.com/wp-content/uploads/2016/11/VESA-100mm-75mm-Template.pdf and a drill bit? should fit on a CBeam XL plate, or add a scrap of aluminum/wood as your mount