I am thinking still leaving in the midnight time frame and staying at a hotel in Pheonix and then somewhere else before Abiline, I don't know those cities well but I'll do research.
When we did a similar journey, our first overnight was in Phoenix, because we have family there. It is about 7 hours from LA to Phoenix. If this trip eventually works out for you, I'd recommend starting not at midnight, but perhaps at 3 or 4 am. You'll then pass through Phoenix without doing so at rush hour, and can stop perhaps in Tucson for your first night. Your next stop could be either Van Horn or Fort Stockton, TX (I'd recommend Van Horn, as motels are generally cheaper). Then Austin. From Austin, Gulfport, MS would be about the halfway point between your sister's house and Orlando. Bear in mind that there are three time zone changes to go through. During the summer, southern California and Arizona are both on the same time zone. But you'd have to lose an hour going east, first in New Mexico, and then another hour just before Van Horn. The third one isn't lost until somewhere just before Tallahassee, FL. When you lose an hour, it will make a big difference in your arrival time at your destination, especially that day when you lose 2 hours. The good news is, of course, you get them back going the other way.

Here's another thought: pick up or borrow a tent, sleeping bag, and a cooler, and camp your way across the country. It would be a matter of finding some state parks or national forests with campgrounds, but it would be safer and far more restful than trying to go almost the whole way without sleep or staying in the more expensive motels. Of course, you have to like camping at least a little.


Donna