If you average them all out, you could make s living. That being said, there are some parks that make good money and some that lose money.
Location, location, location. Though we are blessed to live in Gods country, that means there are many parks competing for gate fees. With a good business model, and keeping an eye on the numbers, it can be profitable.
Just for reference, I have contacted many parks in many states. I actually wanted to do this exact thing a couple years back. Some are better about giving help and others hang up real quickly. From what I gather, it is like any other business. Be able to eat rice and beans and make nothing, while working every waking hour for the first three years and you'll have a fighting chance. The ones that made it, from who I contacted, were passionate and hard workers. Look at the Gap as a prime example. All that guy did was take some ideas from some college kids and made it all happen.
The Gap was a prime example of location. Great location being closest to all the southern most Rock Crawlers. Take that park to the middle of Florida and you would make more money than you could haul out in two wheel barrow loads. If I was willing to relocate, that was my idea. I wish someome would take it an run with it.