[QUOTE=Rakekay... My seat bag isn't big enough to hold one more thing, and clearly tying it around my waist won't work very well on a bike.
[/QUOTE]

That's what the pockets in your jersey are for! Bring your smallest rain jacket, so it will fit in a pocket when you don't need it.

Try to get as much sleep this week as you can - it sounds like you're gonna be too nervous/excited to get much sleep the night before your ride! Just relax - and take a good rest at around 65 miles - I always get pretty grumpy then unless I get really good food at that point.