I've never trained and did SBD either but, I trained for a marathon last summer with out too many gels or that kind of stuff. There are non sugary gatoraid type drinks, I think propel or something is one of them. I would use the shock blocks or luna things only on my really long runs. My shorter runs I felt like I could make it to the end and then just munch on something. IMO The long runs, burned off all those calories plus some so I wouldn't worry about it. I would use my nike+ ipod thing and a long run would burn like 2000 calories
My biggest problem would be the day after my long run, I was always so famished and would eat everything in sight. My body did not like the rollercoaster of burning a lot of calories one day and not many the next.
All the runners I talked to said that while trainging for a marathon, you should not be concentrating on loseing weight at all, because your body needs the fuel. I did lose about 10pounds but since I was averaging 40 miles a week I wanted to have lost more. I feel like the body balances it self out.
Unfortunaltey, I started a stressful job and after the training, could barely fit in 3 work outs a week so those 10 pounds crept back on. Now that its nice out, I'm going to start getting back into things, I dont' know if I can do the marathon again but I need to get my train on!!!
Good luck, you can do it!!