So, yeah, the theory was, be prepared. Procure one impossibly cute toddler-sized backpack with a penguin on it.
Fill said impossibly cute backpack with assorted toys that toddler has never seen, including many toys with a transportation and/or construction theme. For thematic appropriateness, include a blue airplane toy if possible.
Add coloring book, crayons, and/or sticker activity book. Verify crayons are washable and that sticker activity book/coloring book is emblazoned with various familiar, computer-animated animals bearing the voices of famous GenX comedians.
For security, throw in a few old favorites.
Make sure to have plenty of bribes with which to grease the wheels of good behavior.
And lastly, always have a Plan B.
The verdict: 5 hours is a long time to be on a plane with a toddler. Bottom line. Mini did a great job, and the Toddler Airplane Behavior Management System (Beta) performed decently. Some final tweaks are needed: for example, videos do not work exceptionally well when the siren song of the open aisle upon which to run cars calls. Also, mini Oreos and/or Teddy Grahams are great in the moment, and will secure a good 20 minutes to a half-hour of quiet time. However, when the sugar kicks in, you are in trouble. Next time: bring more regular food.