I have found on things like this I need not do anything differently from what I do at home. I mean, think about it. It's a fun ride, a challenge ride. It's not a race and you do not personally have a big prize at stake. There is no need to fall for all the bullshit products that supposedly will give you an edge. If you are able to eat regular good primal food you will be fine. 164 miles on a bicycle is a challenge but it is not super difficult.
I did a 50 mile fun ride once with absolutely no training beforehand and it was fine. I don't think I would have been happy if I'd done the 75 mile route, but I wasn't destroyed or anything and I could have easily done it again the next day. On this ride they fed us so I made the best choices I could. I didn't eat more than I normally do and if anything I ate less, skipping all the breads and snacks and had a modest lunch so I wouldn't feel sluggish. At the celebration dinner at the end, which was chicken and tri-tip, I pigged out as much as I could though.
Female, 5'3", 49, Starting weight: 163lbs. Current weight: 135 (more or less).
Starting squat: 45lbs. Current squat: 170 x 3. Current Deadlift: 215 x 3