Hey mate. If the boat seems in pretty good condition usually its two things in my experience.
The bungs. Even though its in, if you don't make sure you have a tight seal, you will get water going in and when you at the ramp and u do the bung, you would think you have a crack in the hull. Has happened many times to me. Make sure its sealed.
Second is the engine wiring boot like you mentioned. My old seafarer one was bad in terms of the placement of the boot and not being completely sealed. The new boats have some good rigging fitouts now, but the older ones might be more open.