Thanks all. I ended up using Larabars (2 of them) just to get me over the hump -- ate them at 1:30/4 and 2:30/4 and drank about 4 bottles of water and 4 bottles of nuun (2 bottles of fluid per hour). It worked well and I felt great afterwards. I know the Larabars aren't low glycemic, but they at least combine protein with sugars and from real-food sources.