Sorry for the slow reply - and you've probably discovered the answer.
Yes, easy to change. Welding might work. Happened to me away from home, called a friend out with a portable stick welder. Really hard to get a good weld onto the 25mm stub in situ. I got about five miles out of it - with minimal changes. You have no stub there at all so it'll be even harder.
I don't know this, but I think the ball will come off, so could give options for a repair on a bench.
