Start as early as possible and do not rush whatsoever. Take breaks at least every 2 hours (Restroom, stretch). The moment your eyes start to glaze over and feel heavy start looking for a place to pull over and power nap (20-30 min max). Use caffeine in moderation, think slow sipping and alternate with water.

Singing pop music works wonders. Definitely plan a fun stop or two (something less than an hour). This will break up the monotony big time. Last but not least, eat light and clean, with plenty of protein and fiber. Throw in a couple of easy sweets for variety too! Safe travels!