The one I bought platypus big zip holds 1.5 l which is fine for me. I drank before start and had fluid left at end. My body is happy me shoving a load of liquid and food in it before the start. Do this before road races as I often forget to eat in the madness of first hour, so used to it.
No helpers.
Used a bladder, worked bang on. With gels stuffed down my skinsuit front too.
I used the same feeding strategy that I've used for road races this year. I've learnt what I need and can handle now.
You still not right? Sucks you're off bike, sorry. Teach you to do weights. :)