The driveshaft angle looks good. Did it stop the clunking?
I'm guessing it will be fine, but if you find the middle of you addition flexes a bit under load, you may want to add a tab to it that extends up in front of, and rests against, the original bottom lip. It would not need to be welded to the original winch part, it would just act as a bumper. (When winching, the force on the tractor and winch tries to push the winch backward. With your addition dug into the ground, the force tries to move it forward in relation to the original winch part.) In fact, if the strain looks like it is too much for the lower bolts (which is where all the load is borne), A tab in the middle and one at each end, in front of the bolts would add a lot of strength.
It may turn out you don't need to add anything. I'm just thinking out loud here. Worth keeping an eye on, anyway.
