Many parks do not allow the type of fencing (x-pens and the like) that you are suggesting. We tolerate them to the extent we allow them as long as the pet owner is outside with the dogs at all times. The pens are not secure enough to dissuade a motivated dog from escaping to chase people, wildlife or other dogs. Dogs outside and unattended will naturally bark more often than a dog inside an RV. Also some dogs are very prone to digging under fences creating an obvious problem. Long walks on a leash is the best option for exercise if there are no off-leash areas either within the park or nearby. For most people, that long walk is also good for them, there is no better exercise partner than a strolling dog.