You could wear the maxi dress just put a blue jean jacket on or something you cute. You don't want too much bare skin showing, that would be unprofessional. Slacks or khakis, a button down are a blouse.

I would try khakis and a polo shirt something simple

What kind of job at the amusement park IS it? Not many there normally wear gowns. You'd be ready for work in jeans.

Clothes