I could never, ever use a fuel belt. I never understood it, but a few weeks ago I found out I have reflux, and I'm sure that is why. I have thrown up in long races from just having too much stuff in the back pocket of my tri-top (pulls on the tummy area..sorry if that's TMI). So, fuggedaboudit w/a fuel belt! I have had better luck with a Camelbak with plain water and just popping in some gels, jellybeans or whatever.
Others swear by their fuel belts. If you are right over there in Hoboken, and have access to the HoHa, I'm sure you will be able to conjure up at least one or two supported LTR's in preparation for NYCM with water. My running club does one in the Palisades in October...can you get there easily? You'd be welcome to tag along.
Now is the time to experiment with different fuels (solid + water, all liquid, gels, etc). Also, during wintertime when the water fountains are off , I hide some bottles around the park and tighten up my loop a little so I can access them repeatedly. I guess I'd do just about anything to avoid a Fuel Belt. ;-)
Having a "super sensitive tummy" to foods, and not being able to use a fuel belt are two different issues...You might actually love the fuel belt yourself. What have you used for your rides that has worked? Perpetuem is super easy to digest for most people.