I would agree that "The Complete Walker" is a great reference for preparing yourself for a long hiking trip. It's referred to as the "backpacker's bible" by many. He has great ideas on what and how to pack. He also discusses the various gear options, and the tradeoffs to consider. In addition to the thoughts expressed before, here are a couple things to consider:
I would strongly recommend taking a shakedown weekend hike, fully equipped with everything you plan to use on your longer trip. Think of it as a dress rehersal. Use everything the way you expect to on the real trip, particularly including how you'll handle shelter, and water/food. Take the cooking gear and stove you plan on using, and sample your "menu". By doing this test trip well in advance, you can adjust things before your real trip.
There is nothing worse than taking a new type of food on a trip, and then suffering from Montezuma's Revenge out on the trail. We had a member of a trip discover that something Mountain House was using in several of their freeze dried backpacking foods was giving him serious diarrhea. He had never eaten those entrees before, and took them on a ten day hiking trip! Other folks have had various gastro issues with MRE's, although those tend to have the other affect, binding you up. (Always carry things in your first aid kit for both scenarios, some fiber stuff to free things up, and some anti-diarrheal to handle, well, runny situations.) <img src="/images/graemlins/blush.gif" alt="" />
You're going to be carrying lots of water. It's heavy, so you'll most likely resupply regularly if possible. If you're filtering from streams/ponds/etc, practice with your gear. Always have a backup of some purification tab's if needed, since filters break/clog. In your situation, where you'll be in very hot conditions, you'll need to have extra water to deal with delays and problems reaching your interim caches of supplies.
Something people overlook is having a repair kit that is suitable for the things you have that you really would need to fix. You can improvise a lot with some duct tape, wire, zip ties, safety pins, etc, but, there may be a few things that you find are worth carrying spares, or duplicates. That will depend on your gear.
I find that wearing a lightweight, breathable longsleeve top and long pants in a light color keeps me cooler in the heat than shorts and short sleeves. I tend to wear things like the fishing shirts made by Columbia, and pants also. They are vented, very light and packable, and keep the sun off your skin. If you get a little over heated, you can dribble some water on them, and as it evaporates from the material, it'll help cool you down. (It dries quickly). You'll need some headgear with a wide brim or a flap that comes around the back of your neck to keep your head out of the sun.
A first aid kit should be augmented with extra gear tailored to your trip. In this case, you may want to carry a Sawyer Extractor, if it's not in your basic kit. Also, you should have a supply of things to deal with sunburn, and foot issues, probably extra Moleskin/Molefoam, for example.
Having said all that... have a great time, wish I was going! Planning these trips is a lot of fun in the winter. It gives us something to do up here in the Northeast when there's a blizzard coming. Going over the topo's, figuring out your expected route, planning gear and menus, where to camp. Enjoy.
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- Ron