If your Ford is already wired with a Curt or Tekonsha aftermarket light controller... it ought to work. RV puts voltage on the rear lights, controller sees that voltage & turns on the wiring to its own 4-pin.
If you already have one of these controllers installed, plug in some lights and see what happens. If you don't, though, I think getting a splitter for the 7-pin trailer plug is a simpler solution. Plug the Ford into one side, plug extra lights directly into the RV on the other side. RV runs all the lights itself without using the car as a glorified extension cord.
I don't think you can daisy-chain lights if your Ford was wired for towing at the factory. The factory setup doesn't watch the lighting circuit for voltage. It watches the computer bus to see if somebody has flipped the turn signal lever. I'd be amazed if the harness that connects your RV to the Ford is sophisticated enough to work on that level. It would be complete overkill.