I'll share my experience with you. I had one drake prolapse - pretty much all his dangley. We worked to try to save it, then it did get injured and sore. We took sterile scissors (nice and sharp) and I made myself do the cut. He wasn't bothered by the snip at all, it barely bled and healed without much care. A duck's dangley doesn't seem to have much in the way of nerves or blood supply, fortunately. I still have my boy, a pet for years and years, and he's never been fertile after that (some drakes retain enough to get the job done, but not Freckles).
If he's really hanging all out and not going in at all (we were able to get Freckles back in for a day or two at a time), I'd recommend being tough with yourself and see if taking about half of it is enough to allow him to retract it. I suspect a genetic component - my drakes have plenty of ducks and breed vigorously with no problem.
I don't think letting it dry out is good for your drake and the longer it hangs out and drags around, the more likely it is to get damaged and infected. That's my thought. I would give him some time to see if its going to go back in, but realistically, I wouldn't let it go on and on like we did for Freckles.
Sorry that it is sideways!
