I can't tell you what to do, but I can tell you what I've done before long rides:

1. Take the day before off, or ride only very lightly. I like to be completely well rested before a long ride. Plus it gives your buns a chance to get off the saddle, and you can wash your favorite bike clothes to wear for your long ride.
2. Eat lots of carbs the day before, but also make sure to drink a lot, even if it's just water. If your ride is in the morning, eat the previous lunch and dinner carbo-loading; if it's in the afternoon, you'd eat dinner and breakfast carbo-loading, etc. I don't know if eating lots of carbs several days in advance does any real good.
2.a. Eat foods that are familiar to you and that you know won't bother your stomach. Don't experiment the day before your long ride!
3. Eat a BIG bowl of oatmeal (I like it with yogurt, raisins, cinnamon, and brown sugar) on the morning before your ride. Feel full but not agonizingly stuffed. I usually need an hour or so after eating to ride comfortably. A bowl of oatmeal like that will sustain me for 20 miles or more.
4. Bring food with you on your ride that you've eaten before. I always carry 3 or 4 Luna bars for a long ride like that -- I eat at 20 miles, 40 miles, and 60 miles, or whenever I'm hungry. I also carry a banana and lots of water. Eat and drink before you get hungry and thirsty.

On number 4: I can't stress enough the value of eating consistently on a very long ride. I did a 100-mile ride earlier in the summer where I ate sparingly, and it was miserable. I followed that with two 75-mile rides in a row, ate consistently, and felt fabulous. For me a 50-mile ride requires only a few stops along the way, whereas a 70-mile ride is a whole different ballgame. I take a lot more care to be well fed and hydrated on those longer rides (the line for me between long and short is right around 50 miles. 50 isn't too long; 60 is getting there; 70 is definitely long).