Is there anything special about RV electrical outlets?

If the RV outlet is on the tail end of the run (single wire to it) you can add another wire via the insulation displacement connections and add your new outlet to it.
If you have room behind the RV outlet it may be easier to replace it with a residential-style one. An "old work" box is a bit larger than the RV outlet, so you'll have some sawing to do.