Can i weld on a towbar?

So i bought a towbar for my Vitara. It uses the existing tow hook bolt points, relpacing the tow hook plates with drop plates that a bar attaches too, with the towbar bolted tot he bar.

All nice and simple, exept my vitara is far from rust free. The O/S hook plate is missing, and the captive nuts that i need to use on that side of the chassis leg are rusted to obliviion. The N/S is still present, but will need cut off because the captive nuts are just spinning freely.

So my question is, can i just cut the old plate off, prep the area on the chassis legs back there, and weld the 2 drop plates onto the chassis legs all teh way around? In my mind, welding trumps bolting, but i fear there may be a legal snag that prevents me doing this.

Any advice welcome!