My neighbor drilled a hole in his bucket for a ball, and it works fine for him. He is always shuffling trailers around with his tractor, and most of the time, it's with the ball on the bucket. He might have considered the clamp-on receiver hitch, but the first time he needed to move something with the bucket, he had a spare ball and a drill handy, so that's what he did. He has never felt the need to change it.
I've debated buying a clamp-on myself, but just never had much need for it. I've added a receiver to my logging winch, and have another one ready to add to my box blade (I just haven't gotten around to it... for about 5 years now). I have one of those draw bars that goes between your lower 3 Pt hitch arms with a ball that stays on it all the time. It hasn't been used much since I broke down and bought one of those triangular gizmos that go on the 3 Pt hitch with a receiver on it. I don't use my backhoe all that much. If I did, I would definitely either drill my bucket of buy a clamp-on receiver.