Having your own RV and a love for the outdoors are good starting points for becoming a state park camp host, though you might face competition for many positions. Camp hosts don't usually get paid for their work they do, whether it is helping guests or keeping the campground well maintained. But they do get free camping sites, often with electricity, water and sometimes even phone service included, making the positions quite desirable. A combination of the right skills and good communication and timing can give you the best chance of landing the position you want.
Research the Parks
Visit the websites of the agencies that run state parks in the states you'd like to work in and review the information about each individual park. Different parks will likely have different needs. For example, some parks may require that hosts have knowledge of local flora and fauna, so having a background in ecology or ornithology would help. Other sites might require hosts to maintain the park, in which case a background in carpentry or landscaping would work well.
How to Apply
When you find parks that fit your skill set, send in your application by the required date. Include personal or professional information that might make you a more desirable candidate, such as experience cleaning and maintaining bathhouses. For summer positions, there may be a winter or early spring deadline or recommended application time frame. Also, call or email the state park ranger responsible for the park -- information you can find on the state park website -- to introduce yourself. Some parks systems fill positions on a first-come, first-serve basis, but for the ones with a vetting process, that personal contact might help you seal the deal.