Just a few more thoughts. I can't stress enough how important nutrition is on a trip like this. If you fall behind, it will take many days, maybe the entire trip, to catch up. Each day you are behind your pace will fall until you're struggling to do 15 on the flats. Been there, done that.
Take your time before hand to plot your route well. Wrong turns and getting lost will cost you valuable time. For this reason, try to keep it as simple as possible. Route finding after dark is especially tough and will cost you more time, even if you make all the right turns. This might be a good use for a GPS.
Speaking of night riding, it is my experience that your pace at night will fall at least a little, so be sure to allow extra time if caught out after dark. A good, strong headlight can help keep you as close to your daytime speed as possible. My preference is a generator light, but I have done fairly well with 1 watt LED headlights as well. A helmet light is worth it's weight in gold for navigating after dark. You will not have to slow down to read your route sheet, computer, or street signs. My favorite of the moment is the Princeton Tec Eos with lithium batteries.