My second son is a Nathaniel, but I very rarely call him by his full name. He's Nate or Natey! As so many have already pointed out no need to spell her name Caraline. Caroline works just fine and Cara is a fabulous nickname.
In fact, I love the nickname option. My husband was very into traditional names, simply because they sound more professional when they are older. I thought they sounded like an "old man" name when they were babies. So longer names that can be shorten are an awesome compromise for us.
For the most part the first year of both my boy's life I tried to call them by their full name, just so they would respond to it. It was easier with my first son's name, but thank goodness my Mom always calls my 2nd son by "Nathaniel" so he too responds to it. This way when you're at a park, and there are other kids with the same name you can call them by their full name or nickname...and it works when you really need their attention otherwise. Good luck, great name!