Since it is poor during times when no one is around, I'd do some troubleshooting. Are there other towers which give better performance? Do others in the campground have the same issues? If some work OK, you may want to check your network adapter driver, or use another wifi adapter. Certain hardware combinations somehow are not compatible.
How does it work for simple web browsing or emailing off peak?
There are longer distance wifi adapters available-if other hotspots work better . If it is a failure of the park's system and fails during off peak times when it should be working properly, keep bringing it to attention of office.