I did my first RAIN ride this year which was a historically cool day but nontheless I did do it. I only got up to 100 miles about a week or so before the ride. That was my first century and then I did the 160 about a week or two later so I know you can tackle this thing. If you are stable on rollers you are probably a lot stronger rider than you know. Rollers kick my butt! I think you have this thing beat already.

As others have said the trickiest thing is figuring out how, what, when to eat and drink. You can't really find definitive guidelines because it's all so subjective from one person to the next. My advice is just start playing with different combinations now to see how your tummy feels or how you feel energywise while you are riding. OK here's another thing, I'm doing the Hilly and I have NOT trained . I just take it easy, the ride is way too much fun to miss! It's not competitive its all about the fun. I have a granny gear and I'm not afraid to use it!

I guess I'm assuming you are riding clipped in? If not, try getting some inexpensive clip in pedals and shoes (mountain bike style are nice so you can walk around easily, those are called SPD style). Being clipped in really helps me with stamina on a long ride like RAIN.

I hope that helps a bit and would LOVE to see you come down to the Hilly!!!