Once it starts raining you have access to all the bodies you need on the ship. Rewatch every flashback and take notes. Details really matter, and those flashbacks are crime scenes that need to be studied fully. Pay special attention to clips in quick succession, as a clue from another flashback may show the means of death or the killer.

What do you mean by “stopped giving clues”? The clues are all around you. Hair styles, clothing styles, accents, places, etc.

I definitely brute-forced my way through significant portions of Obra Dinn, but the fact that you can do that at all (and it's not TOO onerous) is nice.