How to prepare very soft sandy soil to make a hard and flat base in preparation for laying turf.

Moving in to a new house in Bribie Island next month. The soil is very soft and sandy - we have a caravan hardstand down one side but have to traverse about 12 metres across what will be the front lawn only about 4 times/year- probably Zoysia Empire - dont want to lay concrete - want turf. Please advise best way to get hard flat base in preparation for laying the turf & what additives should I put under the turf. Thank you