Probably more. And you would have to drill a hole anyway. The clamp without a hole takes up considerably more space. You might be able to do it with a suitable m tter and plate.
But I wouldn't buy the stand again anyway. I've never managed to align the screens properly. They have too much play and hang quite low. They also take up a lot of space at the back and the whole thing is heavy.
The USB hub didn't work for long either.
A system with a rigid rail is better for aligning 3 monitors. A gas lift or springs for flexibility.

You need to allow about 5cm by 3.5cm to fit the fixing system under the desk. I can confirm what the other person said: the system is very basic. It does the job but the quality is inferior.