Try a Go Cruise throttle lock. I have used one with great success for several long trips.
Amazon.com: go cruise throttle lock
Also, protect your hearing with foam earplugs.
As others have said - do all of your major maintenance before you go, fresh oil and filter, clean air filter, ect. Make sure your tires will get you there and back, unless you have planned for a tire change on the trip. They sell smaller cans of chain lube that is easier to pack, and together with a zip-lock baggie of rags and disposable rubber gloves, you'll be set!
Take a short trip with all of your 'road trip' gear installed and try it out before you go. (It was worth repeating.) And although I've done it, modifications done the night before you leave are generally a bad idea.
Duct tape, reflective or shiny if you can get it, is great for repairing damaged soft luggage (or holding other stuff together until it can be repaired - like lights and fairings). Bungee cords will help hold said damaged luggage together and on the bike. Buy a new package of assorted bungee cords - they're relatively cheap; because you don't want to have to fiddle with old, dried out bungees when you really need them. Zip ties, in assorted sizes. At the very least, a basic FZ oriented tool set.
Carry more flat repair kit than you think you'll need. I carry a C02 type as well as a plug type with tire goop and a small air pump. A set of jumper cables is nice to have too. Road Gear sells some nice accessories, like flat repair stuff and jumper cables.
http://roadgear.com/tire-repair-bike-maintenance-c-24_41.html
A helmet communication system is nice too, and most will allow you to listen to music and make phone calls via blue tooth. I use a Sena SMH10 and am pleased with it.
As long as your gear is well suited for rain use, and you have the ability to remove warmer inner layers, you'll be good. If you will ride at night, a small microfiber towel is nice for cleaning bugs off of your face shield. You can dampen and rinse it when you get fuel (this is actually great in the daytime too!)
Be prepared to ride in the rain. (This should probably read: Be confident of your ability to ride in the rain.)
There's more I'm sure, and I know I repeated some stuff, but that's probably most of the important stuff.