I am planning on racing at Musselman 70.3 half Ironman is July. I have never done a race over an Olympic distance and the nutrition & hydration area is a bit of a concern for me. I have purchased a case of Gatorade Endurance and plan to use it primarily on the bike and again on the run at the hydration stops.
My bike has a Torhans 30 oz hydration system and dual rear cage for 2 - 24 oz Gatorade Endurance bottles. I plan to drink the 30 oz in the Torhans and 48 ounces directly out of the Gatorade bottles from my rear cage, thus not ever stopping at aide stations on the bike route. On the run I will use the 4 aide stations for Gatorade Endurance.
My goals times are as follows…which will help determine how much to consume:
Swim: :33
Bike: 2:35
Run: 1:45
Overall: < 5:00
I tried to do a Liquid fuel plan when I was stating out at 70.3 races. I was using ESF it it makes any difference. I was not success on that plan. I would start to fade about 35 miles into the bike leg and the run was a total death march. I found for me I needed more calories than I could get from a liquid fuel plan. Eating a full cliff bar 30 miles into the bike or taking a gel every 20 miles on the bike got me to where I needed to be on bike leg. Taking gels every 30 minutes on the run, and coke from the aid stations when I started to feel the tingling feeling in my legs that I get about 10 minutes before a bonk, helped me get through the run leg.
In addition to the bonks that I experienced in my first 70.3 races I also was getting major leg cramps in the 70.3 races. Some times they would hit after about 45 miles on the bike but they always hit me on the run. Sometime 5-6 miles in, sometime 8-10 miles in, but I could not get through the run with out cramps. I started taking an electrolyte table 30 minute before the swim, ever 20 miles on the bike, and ever 45 minutes on the run and that helped me get through with out cramps.
Racing in July you also might have a very hot day and have to deal with the heat. There are strategies for that. You might have to deal with blisters, chaffing, etc. and there are things that help with them too. There are lot of things that I didn’t know about in my first 70.3. I learned the hard way, but have done enough of them now that I know what works for me.
My goal at my first 70.3 was to go under 5 hours. I didn’t make it . It took me about 3 years before I finally got under 5 hours. When I did my splits were Something like a 45 minute swim, 2:32 bike, 1:32 run. So my goals since then has been to do a 35 min swim, 2:35 min bike, 1:35 min run. It makes it easy to keep track of the splits if that end on the 35 minute mark. 
I got a bunch of the individual Gatorade Endurance packages a some races I did in January and February. I don’t really like the favor but they work just fine. I didn’t look up the calories, carbs, electrolytes in them since I wasn’t using them for an endurance race, but I know that the the ESF that I used in my 70.3 races is way higher on electrolytes. If I were to use the Gator Aid Endurance I would probably need to double the number of electrolyte tablets I took. If the calories are lower I would either mix it thinker or, more likely, just take two cliff bars for the bike at miles 20 and 45 instead of just one at mile 30.
You can use about anything to get to the replacement levels that you need to race well. If you are getting more from your liquids you can go less on everything else. If you are getting less from you liquids you need more from everything else. If you are mixing liquids a lot thinker than the directions that is probably the way to do on a liquid only plan. You just have to remember to get your fluid too and that might be easier to do if don’t have a really thick nutrition bottle to chug down. On hot summer days I have drank a 24oz of fluids in my first 2 miles on the bike and gone through 5-6 water bottles in the saddle. If you don’t do well with solids do the thick water bottle mix. You might not be at odds with all solids though. Some people take chocolate squares, all types of candy, homemade bar mixes, and other non traditional things that they like and can stomach. Use what you like. 