I use a very simple mix of powdered stuff for my fuel bottle. I mix a 2 hour (600-700 calories) batch for each fuel bottle. I will have about 30 - 40 premixed cannisters (plastic containers from a medical supply facility) that the crew can just pour one at a time into the fuel bottle, add water, shake a bit (very, very viscous and without lumps) and hand off to the rider. I will also bring one gallon cannisters of the powdered stuff (Maltodextrin, Whey protein, Perpetuem) in the event we run through the premixed cannisters.
The water bottles the same. I use a predetermined amount of Hammer Endurolyte powder for each 24 oz bottle. Same thing: smaller plastic container that the crew pours into every bottle of water. Mixing may help but it doesn't really matter because the powder is very fine, though sometimes gritty. I will have several bottles of Endurolyte in pill form, too. These can be useful to take on an `as needed' basis in hot and sweaty times.
I'll be drinking one bottle of Ensure Plus at least every two hours. That comes in it's own bottle and the only thing the crew will need to do will be to twist off the cap and hand it off to me. I'll gulp it down quickly so this can be done in one rolling bottle handoff. On ped handoffs I'll just drink it and flip the empty Ensure container behind me for the crew to pick up (unless I'm going so slow all you'd have to do is a little slow trot to keep up with me).
I'll also be drinking/consuming one can of Campbells chicken soup every one or two hours. It's semi-liquid and has meat, noodles and a lot of sodium. Again, this is easy to deal with. What I'll ask the crew to do, however, is to put the chicken soup in a small container (that I'll bring) that will make it easier to pour out of while riding. (The can tends to `hold onto' the noodles and chicken making it clumsy to shake and empty while riding).
Periodically I'll ask for an aspirin or ibuprofin. Frequently I'll ask for a calcium pill (Tums) to deal with potential calcium depletion in the heat and sweating. Once each day I have a few medically prescribed pills to take. I'll put those in separate individual containers well marked. (Despite recent reports about the beneficial effect of Viagra while doing long endurance work I'll not be ingesting THAT ***!).
There will be times when I will just need to `overhydrate.' That is, I'll want more water than one thinks I should have. This is important to do, as long as I make certain I'm attending to sufficient electrolytes (Endurolytes, Tums and chicken soup).