I agree that "going back" is not the safe thing to do. Reaching across while still maintaining a reference point is more like it. We also brief that, if you end up on the surface, you don't go back down. On the way out, after having sorted yourself but still with the wreck, do your best to ensure your buddy made it out. I think it might be different in a larger airframe where you can't just reach out and grab your entire crew...
We didn't do night dunks, but we don't do much of any night over water work. Pretty frowned upon unless it's rather important. I think if the event happened at night, it would be a miracle of anyone made it out expediently let alone did buddy checks on the way out.
Mike