Thanks for the comments guys.

I can get a male for the C.d.unicolor next year, I don't have much space left so I might get into a breeding arrangement with another keeper, no problems there.

As for sexing, usually it is a two people job. One can restrain the snake with a tube, while the other probes it. But most of my snakes, especially the death adders, can be sexed just by looking at the tails.