You've got a plan.
Cold comfort to you, now, but for everyone else's information I have a habit of checking my passport when I first sit in the car after leaving my house for an international trip. I get in the car, say "Wait a sec", positively confirm that I have my CURRENT (not expired) passport in my purse, then say "Go".
My final check is in the car, not in the house, as it is easy to leave something on the kitchen counter or table near the door. I check when I'm actually in the car.
Back in the days of paper tickets, I did the same with the paper tickets.