This is a very good thread, and a timely one. My family is leaving tonight for a 1-day trip to Legoland. (4 hour drive)
I've found that I am sensitive to bagged salad mixes. At least, that's my theory based on a few restaurant salad experiences, including my last trip to Legoland (spent a couple of hours in much distress that evening).
We are staying at a hotel with free breakfast, a fridge, and a microwave, but only for one night.
Although my spouse and kids and MIL will probably prefer to eat in the park (and I am going to let them), I will pack a sandwich. I have a smaller cooler lunch bag that will easily fit in my backpack. I have leftover mayo and mustard packs from work lunches. Some raw veggies, a water bottle, a turkey sandwich, and a cold pack should keep fine on the drive down, the night in the fridge, and the first half of the day in the park.
We will stop for dinner on the way home, or before we leave. Unsure about the best time to leave Carlsbad traffic-wise, when it involves driving through LA. Probably 6 is better than 5.