I didn't see anything on those lists about removing the hull plug(s), putting them in a plastic bag and attaching them to the steering wheel or throttle. They can be put in a cup holder, but that allows for them being moved and mis-placed. If the boat somehow gets wet and the plug(s) aren't out, bad things happen.
RV anti-freeze is bad for the heads. This was hammered into our heads at MC training every time I went. It may not happen after one time, but it's not worth risking, IMO.
If no anti-freeze is used, remove the hoses on the engine at their lowest points and turn them so any water in them can drain out. Crank the engine to clear the raw water pump or loosen the cover plate, to allow any water that's above it to drain out.
At some point, the bearings and brakes on the trailer need to be serviced- at least check them, annually if the boat is trailered frequently.