How best to improve a primitive RV site to rent it out?

Better check with the county/local and state governments, especially in NY where you can not take a dump without some type of expensive permit, usually proceeded by a pile of red tape. We used to live north of Albany so I know all about how things work in that hole of a state.

That's a great area though, and I personally would jump at the chance to camp on sites such as in your description. No cell service is a huge bonus as it will keep the riff raff away