Well, I was going to comment on the distance, but I'll keep my mouth shut on that one.
I presume that your 18,000 mile service is complete? If not, make sure that's done, and your annual or every-other-year service items are up to date.
I would highly recommend the
Stop-N-Go Tire Plug Kit (the smaller one, withOUT CO2 cartridges). Just follow the instructions carefully, and it's super-easy to repair a tire. Throw a tire-pressure gauge in the kit. Also, pick up a 12V compressor, this one is small and reasonably priced:
Slime Powersport Tire Inflator. You can also purchase an el-cheapo $15 one and tear it apart, but the Slime is a nice package. Bring along a piece of rope. If you have to work on the bike (especially when plugging a rear tire, or removing the rear wheel), you want to tie the centerstand to the front wheel, so you don't topple the bike.
Make sure you have someway to plug it in! If you have an accessory socket, you can get an accessory plug to SAE connector to plug the compressor into the socket. If you don't have an accessory socket, it's probably a good thing to install before you go for the compressor, cell phone, etc. All the wiring is there, you just need the BMW part.
I would get the Omega QD's and at least have them with you along with some extra O-rings for the disconnects. Then, if you have any reason to remove the tank at all, replace the QD's, too. BUT, I am an ease-of-maintenance freak and chaging the QD's was the first thing I did after buying the bike. You are not likely to need them for your trip.
Another good thing to have, but probably not necessary for the trip, is an upgraded toolkit. When doing maintenance and repairs on your bike, you should be using the toolkit that came with it. Whenever you run across the need for a tool that's not there, add it to the kit.
Make sure you have spare fuses and a few spare bulbs. I carry one spare tail/brake bulb and one spare turn signal bulb. If I didn't have auxiliary lights that were on all the time, I would also carry a spare headlight bulb. I stuffed two bulbs in some foam and slid it in the electrical box in the slot just forward of the fuses.
I also like to carry a bungee net and/or cargo straps with me in case my side cases shrink during the trip. Extra water is good advice. When I lived out west, I'd stuff a Camelbak bladder in the tankbag with a 90 degree bite valve. I could stuff the tube up my full-face helmet while on the move.
Good protective gear and rain gear is a given.