I will be making a similar trip in the same direction next week. From San Antonio Texas to Miami Florida. I also plan on making it in a straight shot. Some of us road warriors simply enjoy the open road. I have an 07 Expedition Limited with 44k miles. This is my first Ford vehicle, but i have driven other F150's (company truck) with 100k+ miles on them, both long hauls and short hauls, with no problems. These trucks are truly made to withstand just about anything you can throw at them. I work in the oilfield business and run these trucks through some of the roughest terrain imaginable, for long periods of time (14+ hrs a day). Some companies run their trucks 24 hrs a day with no problem. You just need to keep up with the maintenance.
Like some of the suggestions stated, check your fluid levels and tire pressure. I plan on running my tires at 39 psi (cold) for my trip. Set your cruise and enjoy the ride. You definitely want to bring some extra cash in your pocket. Everyone blows their budget in Disneyland. Hope you enjoy the trip.