On my Tarmac I sometimes use some double sided Velcro to put a extra bottle on the underside of my top tube. And I have for extreme cases put one on the underside of the down tube. So with four bottles on the triangle and with Jersey pockets available too, you can carry a lot of water bottles.
Camel backs are fine. I'll never notice if you have one on unless I'm stuck to your wheel. For me I prefer to not have the weight up there.
I put my carbohydrate in my bottles so I don't have to fumble with wrappers often while riding. I do take some gels, power bar, Snickers bar or something on longer rides. Or sometimes a bag of raisins, dried figs or dried apricots can be a real treat.