You do have to cut the rear undertray to clear the socket for the swan neck and the electrics, but certainly not the wheel well.
I have noticed there is a difference between the swan neck on early and late versions, I think changing at the point where the bumpers became two-piece. I had a factory bar on my '99, and I have just put the same bar on my 02 but the swan neck doesn't clear the bottom of the bumper. I'm going to have to cut a slot about 2" deep to clear it properly.
Having also seen a proper 02 factory bar, the swan neck is a different shape, obviously to clear the later bumper. So, having waited a year for the unobtanium towbar in the first place I now have to find a new swan neck for it, or hack up my bumper which will be visible when the bar isn't in
If there is a genuine bar available, buy it, especially if its that cheap. Having fitted many different bars in my time, the factory (Westfalia) bar for the D2 is a no-brainer for ease of fitment and quality.