If a DEC officer boards a boat containing sleeping people, at
night, and they bust in your door and are shot as intruders, does the court
consider the boat "your castle"

The cops will be a lot more likely to shoot you, they are trained and wide
awake, with their guns at the ready. All reaching for your gun will do is give
them a reason to shoot.
Your wrongful death suit may address things like warrants and identifying
themselves prior to the entry but they will still win the gunfight.