Check your visit time permits. You may be the same as Canadians & a few other places permited 180 days in a 12 month period, not calendar year, visa free.
No, you cannot get off the plane, catch a taxi to a dealer & drive off in your own RV in a few hours. Not if it is a one time trip. Not if it is multi trips over multiple years. There are a few hoops to jump through.