This is what happens when you have too much tongue weight...

You should never, ever weld on a truck frame.

I have seen a few logging truck frames that were severely cracked welded and they were back to work with the same heavy loads in the rough terrain without issue..

Having said that,I would never weld on a frame unless it was in dire need of it,then I would take it to a competent welder with the know how to do such work the right way.

It certainly can be done but to weld on the frame for TC mounts isn't to bright..There are other ways to get the same results.