My guess is they didn't hear the boat coming because they were probably drinking (or other?) and having a good ol time. Maybe even had some music on. Stargazing takes darkness, not quietness! Not seeing the boat coming? I guess if you are staring up at the sky you wouldn't see a boat coming.
If this step is needed we call it the DMV department of motor vehicles. There is a back log of appointments and few of the DMV are open without an appointment. Call the state you plan on purchasing the trailer well before you need to visit them if at all. It was 5 months to retitle a motorcycle to a new owner just a month ago.
Art
How stupid do you have to be, to be sitting in an unlit boat in the dead of night while you can hear another boat approaching and not turn on some form of lighting to make your presence known?
Oh wait, they couldn't hear another boat approaching or see it approaching with navigational lights on. Why would that be?