You get to go through the Truck Crossing, but so do all the other commercial vehicles. The train will be leaving too early in the am to meet the ship. I'd definitely do the ships transportation, but I think you're cutting it far too close. It's about 3 1/2 hours drive down to Seatac from Canada Place and that's without any wait at the border. The bus isn't going to leave until it's full.
So best case scenario, you're away from Canada Place by 8:30, 45 - 1 hour at the border, 3 1/2 drive, 90 minute check in at seatac...that puts you at 2:30 with everything going like clockwork.