Is "Skye's The Limit" a good name for a book?

It's actually quite good because it can have several different meanings. If she's very sure of herself to the point of being annoying to some people, then it might be said that she's "the limit". Your meaning is good as well. However, if you're going to use the name in the title, I'd have her like her name. It will be confusing to the reader if she's always referred to as Jesse.