Yea, I was thinking it would be better to weld it on. If the steering box wasn't in the way I'd cut out the tube and weld the winch plate in it's place. That would be more than strong enough and the bumper could still be bolted on.
It might be more effort than it's worth. It's just that lately I've been in the mood to hack something up. In any case I can ponder it over till the weekend.