You can install a two chamber septic tank near your RV pad. Install a typical drain ( like you hook up to at a park) and run the drain line to the tank. You can install a duplex pump system in the second chamber of the tank. When set up, the pumps will alternate and pump the effluent up to a new distribution box, and then to your leach lines. Or you can put in another system similar to what you have in the basement, and pump it all up to the existing septic tank. All of which requires permits from the local jurisdiction.