Colonial nations are... to put it nicely weird... when it comes to reflecting how they were in reality or how you'd have them. The Florida issue I'd rather be able to keep that land as part of Spain Proper rather than create a Colonial Nation in Florida, Especially when my goal is funneling trade to the Seville Node, which means ignoring most of the East Coast of the U.S. If there was a checkbox that allowed you to block creating or giving land to a colonial nation i'd be for that in a second.
With the bigger thing about California, Lousiana and Texas and such. We'll talk Louisiana for instance, While France claimed all the Louisiana territory, and that territory swung in ownership. Most all that territory wasn't colonized until the 1800's after selling it to the U.S. Most of what was colonized was Louisiana (the modern state) and the area around St. Louis. But you and the AI easily takes all that land well before then.
Similarly the Texas Part of New Spain (or Mexico) was sparcly Populated (same for La Florida where the Majority of people lived in and around the around 5 or so Forts (which can not be simulated by the game w/o creating a colonial nation) However the AI in New Spain (or Mexico) colonizes the Texas Region first, and it's usually heavily colonized by the 1800's. There were not that many people living in California, Texas, Arizona, New Mexico or even the Northern Mexican region until into the 1800s, mostly centralized in "urban" regions like San Antonio, Los Angeles, San Fransisco, and so on.
The English colonies on the East Coast were probably the most heavily populated regions outside of Mexico in North America, and in General besides Mexico and the Caribbean, and possibly Canada, really the only things considered True Colonial Holding until the 1800's on the entire continent.
But the way the Game works, it's kind of hard to simulate this.