Assuming 508mm is accurate for the monitors outer-most width, I think you should just about be OK.
I have a 21" Polo, and since I scratch-built my cab I allowed a bit more than 2mm clearance (!), but that said, the clearance was mainly there 'just to make sure', and to allow for a bit of a bezel.
Not really much help but here's a pic of how I mounted my screen: