Kohree 50 amp to 110V Adapter RV Plug, 15 Amp Male to 50 Amp Female RV Power Adapter Cord 12", NEMA 5-15P to 14-50R RV Dogbone Electrical Adapter

Wire it as a regular 120v/20A outlet. Get a 50A to 15A or 20A adapter. https://a.co/d/0aeNVPfJ While a 50A RV does use 2 hots, they're typically wired with 120A loads only, so they can run off a 30A TT or 20A outlet