My wife and I lived onsite in our travel trailer for more than two years while building our house ourselves (Eastern Panhandle of WV). I installed a 30A breaker in the temporary panel and an RV receptacle about 80 feet away on a tree near the trailer. Ran 10-2 UF and just laid it on the ground. We never had an issue with running the air conditioner or anything else. Since the setup was clearly temporary, the inspector never said a thing about it.
You can buy extension cords with RV connectors but they are kind've expensive and not useful for anything else. I've still got the UF, waiting for the right project to come along.