We have two dogs, including a 100 pound hound dog. A pen would not work for us, so we connect a plastic covered cable between two trees at about 7 feet up and connect leads to the dogs for a dog run. We do this at state and local parks and have never had a problem with them.
Once the dog run is set up, it's easy just to connect the dogs to the run near the RV. The dogs like the freedom to roam or just sit near us. Occasionally we have to untangle the leads, but it's a good fit for our camping.