Private RV parks are almost always trade a spot for hours work. Very poor deal.
State parks are usually volunteer, you get a free site for working, usually around 20 hours a week. It works for some people.
The job you want is as a National Forest Campground host. I did it for 4 years and loved it. Your paid for every hour you work and you get a free site to live in. Let me repeat that, you get paid for every hour you work. And you get a free site to live in.
However, most of those job end in September, although some go into October. You are very unlikely to get those job now. If you come to the RTR, it's very likely you can get a job there for next summer.
Amazon is a great job, but they are getting harder to get and it's probably too late now for this fall.
Sugar Beet harvest is also a very good thing, but, it's too late for that now also.
If you come to Quartzsite in November you are very likely to get a job with a vendor tent but you have to be bold enough to go around and look. If you are, it's very likely. They usually pay under the table. I think everyone I know who went to Quartzsite in November got a job if they really beat the bushes.
Bob