I would find out if they have a Mother's Room. Disneyland and Knott's Berry Farm both have rooms with rocking chairs that are behind curtains where you can nurse discreetly. I alway use my boppy when nursing so I placed it in the basket under my stroller and when I needed to nurse my then 7 month old daughter I went to this room boppy in hand.
Disneyland's room is great. It has everything you could possibly need for a baby.
Or I would just get a cover and nurse in public. No one will see anything and anyone with a problem with it needs to get a life.
But if you are more comfortable with the pumping and feeding with a bottle, I would start a few weeks ahead so that she is not confronted by all these new and different situations at once. If you do it this way, you still run into the problem of not being about to express the milk in a timely way while you are in the park.
Good luck and I hope you have a great time at Sea World!