Doug Mo would tell you to pretty much stick with Bud Light as a training beverage and that mostly thats all the training you would need
Alternatively, you could practice riding as fast as you can for twenty minutes, then getting off and waiting by the side of the road for an hour, and doing it again about twelve times.
Seriously, It was once said to me that the really hard part is just having the adrenaline turn on and off a whole bunch of times a day. And it does become a pretty long day, even if things go smoothly. And I have found that unless you can find some roads where you can really just kinda haul ass for a while without getting in trouble, there is not a lot we can do on the east coast to "train." The events themselves are the best training there is.
Getting in a modicum of shape will make you ride better, but thats just true generally and isnt a dealbreaker for this at all.