BTW......nice bike. Love the color. Long rides? 30-40-60 milers? I am totally a road rider on a Trek Madone carbon fiber bike with caliper brakes <. I am old school still....LOL! I have a water bottle carried on frame. In a 20 mile ride I typically consume only 1/3 the contents (Zipp Fizz). But that too depends on profile of the ride and temp. I use to live in the mountains and would do a 16 mile climb up Mt. Pisgah yearly and even though that sounds a lot, the humidity and temps there were not so bad and fluid intake was not a issue to warrant two bottles. However, I have moved back to my hometown where I grew up and temps are mid summer in the 90’s and humidity through the roof so intake is different.
You will find your need after a few rides. As to camelbacks on a roadie.......nahhh. But if that works for you, don’t let anyone tell you otherwise.